Google's past conquests have been varied, but they have all been smallish Internet companies that are doing cool stuff. I'll go through them here, with a brief blurb about how they were acquired, and what has changed in the post-Google era.
Deja News (Google Groups) - This web-based Usenet archive started life in 1995. Between 1999 and 2000, Deja overexpanded into a comparison shopping portal. Losing money, Deja sold the shopping component to eBay in late 2000, and it became part of Half.com. In February 2001, the big G entered the game and snatched up the Usenet archives, reintroducing them as Google Groups and extending them back to 1981 with the help of private collections. Today, Google Groups features Deja's Usenet, mailing lists, and Yahoo! Groups-esque features with a Gmail-like interface.
Outride - Outride, Inc. was an information retrieval spin-off from Xerox Palo Alto Research Center (PARC). Google acquired certain technology assets in September 2001 and quickly integrated them into its search engine. Outride.net currently forwards to Google.
Applied Semantics - Google bought up this contextual advertising company in April 2003 and used it for its AdSense/AdWords services, allowing it to compete with Yahoo!'s Overture.
Kaltix - This 3-person personalized search startup company was quickly picked up by Google in September 2003. Kaltix formed the foundation of Google Personalized Search. Kaltix.com currently forwards to Google.
Blogger - Blogger was the flagship product of Pyra Labs. For a long time, Blogger was free of fees and ads, but it wasn't making money. After the original capital for Pyra dried up, a number of employees resigned, including the co-founder. In an effort to become profitable, Pyra introduced the ad-powered Blogspot hosting and the pay Blogger Pro service. It wasn't quite enough, and Pyra needed more resources, so Google stepped in during 2003. Blogger was redesigned by professional web designers in May 2004, and is now one of the most-used blogging tools.
Picasa - Picasa, a $30 photo organizer program, was first released in October 2001. In May 2004, Picasa announced integration with the Google-owned Blogger, and in July 2004, Google bought the company. Soon, Picasa was free, and it featured Google trademarks like an "I'm Feeling Lucky" button. The software routinely wins awards from leading PC publications.
Keyhole - Keyhole is a digital mapping company founded in 2001. Presumably to cut out the middleman for the not-yet-released Google Maps, Google bought them in October 2004. Since then, there has been an immediate price reduction for the Keyhole software (from $69.95 to $29.95), and integrated satellite photos in Google Maps.
Zipdash - Google acquired this traffic/mapping company in 2004 and put it to work in Google Maps. Although the acquisition was not publicized, Zipdash is mentioned in Google's 2004 annual report.
Where2 - This Australian mapping company was also mentioned in the 2004 annual report, but not much is known about it. It also had something to do with Google Maps.
Urchin - In March 2005, Google acquired Urchin, a web analytics and statistics company. Though we haven't yet seen what they're up to with it, it will probably be used with AdWords/AdSense, with statistics about clickthroughs and such.
Dodgeball - Google acquired this two-person cell phone social networking company in May 2005. The company was looking for investors, and Google apparently fit the bill. So far, nothing has happened with this company, but it will probably have something to do with Google Mobile.
So those are the companies Google has acquired. A common misconception is that Google has only been acquisitive since its (in)famous IPO. As shown here, however, the IPO has only made it easier for Google to buy companies it likes. Pre-IPO, from 2001 to August 2004, Google acquired 6 companies. Post-IPO, from August 2004 on, Google has acquired 5 companies. In the year since the IPO, Google has almost matched the number of companies it acquired in the prior three years.
Now that we've taken a good look at the past, here are my picks for the companies Google should, could, will, may, perhaps is considering to, would be cool if they were to, might acquire.
These companies are tossed around quite a bit by bloggers as possible Google fodder, and they would integrate well with Google's current offerings and its future strategy. They're all pretty small companies, but quickly becoming popular among web users in the know. No surprises here.
Technorati - If Google is the average person's homepage, Technorati is the homepage of the underground, tech-savvy web user. Technorati is a blog portal whose average visitor enjoys podcasts, Wikipedia, and the Daily Show with Jon Stewart. Providing more cutting edge results than a normal search engine, Technorati would integrate well with Google News and/or Blogger, and could perhaps feature blogs on the Google Personalized Homepage. Technorati is somewhat similar to Bloglines, which was purchased by Ask Jeeves recently.
Buzznet - Yahoo! beat Google to the punch by acquiring Flickr, one of my candidates in the first draft of this article. Like Flickr, Buzznet is a photo hosting and sharing service that features unique tagging features. It is possible to browse by tag and see all sorts of interesting stuff. Buzznet would probably jibe with Picasa's Hello photo posting service, perhaps include some sort of photo-Blogger, and integrate well with Orkut.
Koders - Koders is a search engine for open source code that works remarkably well. With the recent push for plugins for Google Desktop search, Koders would be an interesting addition to Google's software initiatives. It would make sense to combine with Google Code and Google Linux Search in some way.
GuruNet (Answers.com) - Recently, Google stopped linking to definitions on Dictionary.com, and started linking to Answers.com instead. Answers features a wealth of information about different topics, and uses Wikipedia for much of it. Since Wikipedia's non-profit status rules it out as a potential Google acquisition, Answers.com would be the next best thing. It also would help improve Google Q&A quite a bit. Interestingly, GuruNet is a publicly traded company (AMEX: GRU) with a market cap of about $100 million.
del.icio.us - This social bookmarking and tagging application could be used to improve Google search results, and perhaps integrate with Orkut in some way. Were Google to buy Buzznet as suggested above, this would work well with it.
StumbleUpon - This unique browser plugin and service would probably improve Google results and add a new level to the venerable search engine. It would probably combine with the Google Toolbar in some fashion, since the two have some similar functions.
Propel - Similar to Google Web Accelerator, Propel claims to speed up your browsing experience. The company is run by optical mouse inventor Steven T. Kirsch, who is no stranger to buyouts: his Frame Technology Corp. was purchased by Adobe, and his Infoseek was bought by Disney. This could help Google out with Web Accelerator, which it has been having trouble with.
From Left Field
Here are some companies you probably haven't heard of, and some companies you know very well that fit in less well with the Google plan. It is not too likely that any of these will be bought by Google, but keep in mind, most of Google's past acquisitions have been unexpected.
Audioscrobbler/Last.fm - So far, Google hasn't made any inroads into the music industry. However, these sites together form an interesting, Google-ish service that uses algorithms reminiscent of PageRank to calculate the top artists and similar info.
TiVo - TiVo is a little too big and a little too well-known to be bought by Google. Also, Google's experience with hardware is limited to Google Search Appliances and similar. But, TiVo would work well with Google Video. TiVo seems to fit better with Apple Computer's media plans than it does with Google's geek mentality, though.
Icosystem - This swarm intelligence company might be useful for radical new spidering algorithms or some new form of PageRank. It's only peripherally Google-ish, though.
Monster - Monster is the most popular job search site. Some bloggers have tossed this idea around, touting various forms of integration with other Google services. They also mention that Yahoo! owns HotJobs. However, one wonders whether Google is interested in this market at all.
Coral - This caching service would probably be interesting and useful for Google's own cache. However, it is run by NYU, so it's not a commercial company, and may not be up for grabs.
The Open Directory Project - The definitive web directory has long been partnered with Google for the Google Directory. But the Google Directory hasn't been updated in a very long time, and it still sports the old tabbed Google design, which lacks links to Froogle and Google Local. Although the ODP is owned by Netscape, Google should have sufficient cash to acquire it since the IPO.
Stayhealthy/Fitness Expert - This online health company doesn't offer content a la WebMD, instead providing health and fitness hardware, self-test kits, and a kiosk joint-ventured with IBM. The hardware interface is web-based. As with TiVo, Google's limited hardware experience may be a problem, and one wonders whether Google is interested in the health and fitness space.
World66 - World66 could be Google's answer to Yahoo! Travel, with some work. Its Wiki style, however, might be too wild for Google's liking.
My Way - This image ad and popup-free page is very Google-like. However, it's redundant to existing Google offerings, and these days having no popups isn't as big a deal as it was 3 years ago. It might compete with Yahoo!'s portal, though.
So there you have it, my picks for Google's next additions, and some less likely, but nonetheless interesting, possibilities.
There are also a number of other companies that would appear to be a good match for Google, but cannot be for various reasons. Many of these include non-profits like The Internet Archive or Wikipedia. Others like IMDb are owned by other larger companies which would not sell them (in this case Amazon.com), and still others are open-source driven like BitTorrent or the Mozilla Foundation (also a non-profit) and would not make a good fit in a corporate environment.
Many of the companies listed above might not be considered by Google alone. Microsoft, Apple, Amazon.com, Adobe, and Yahoo! are just a few of the web giants that have made it a habit of buying attractive Internet companies. I bet they're regretting that they never approached Google itself with an offer!