Google acquisitions:
JotSpot, Measure Map, UpStartle, Jaiku (2006--07; undisclosed)
Yahoo acquisitions:
Upcoming.org, WebJay, del.icio.us, MyBlogLog, Jumpcut.com (2005--07; undisclosed)
Winner: YAHOO!
(By a nose.) With web applications, Google tends to buy a site and immediately close it for integration. Some technologies resurface - such as UpStartle's word processor, Writely, which became Google Docs - while others vanish - such as wiki site JotSpot. Yahoo prefers to leave branding and operations alone, and both Upcoming.org and del.icio.us have increased web traffic since being purchased. WebJay, on the other hand, was briefly integrated into Yahoo Music and then shut down.