What if, on August 19th, 2004 (Google's first IPO), Microsoft decided to buy out the majority of the company? How would the history of the two companies diverge now that they are united under one banner?
Google would still be the dominant search engine but it will probably shortly be changed to be like Yahoo like site. Gmail never gets out of closed beta, or gets merged into hotmail. Docs never happening. A lot of Google Labs apps never get made, by virtue of them now following MSFT's corporate practice