I don't generally spend a lot of time surfing the internet, but if I'm looking to burn some time you can usually find me on one of these sites.
purevolume is a web site that allows musicians to post songs for people to listen to and occasionally download. The music selection is extremely broad, but focused on more punk, hard core, etc, and most big name bands aren't going to be found here. Check it out to hear some new music.
I enjoy a good (free) sudoku every once and awhile, and this site keeps track of your times at each difficulty level and can even rank you against the rest of the people who use the site.
The Phat Phree is a fake news web site that has some of the funniest articles I have ever read. It tends to be hit or miss, but when you find a good one you'll read it 20-some times and cry from laughing so hard. I suggest this fake letter to John Madden. Ethan Albright Strikes Back