I think it depends on what kind of site that you mena? If search engine, google is absolutely the best, and for the social networking facebook is the best...
Depends on what I am working on for the day or week. If I am working on a site then mostly that particular site. I do go to hotmail and gmail everyday, as well as my own sites and check my stats. Otherwise probably google...msn and yahoo for news. Not much of a facebook junkie lately. Guess it depends on ones hobby, interest, or current events even sometimes.