Well I have to admit I find it hard to believe that people search for Facebook and related terms but there you go.
Here's an article that describes the details;
New York, N.Y., Dec. 29, 2010 – Experian® Hitwise®, a part of Experian Marketing Services, has analyzed the top 1000 search terms for 20101 and Facebook was the top-searched term overall. This is the second year that the social networking website has been the top search term overall, accounting for 2.11 percent of all searches.1 Four variations of the term "facebook" were among the top 10 terms and accounted for 3.48 percent of searches overall.
Oh and Facebook was the most visited website; doesn;t say it was the stickiest too but I'm sure it was…