A Google search for guitar tabs will yield lots of results where you can find song tabs but I will mention a few sites that I like:

Ultimate-Guitar.Com is the fastest growing guitar community on the net, your #1 source for chords, guitar tabs, bass tabs, ukulele chords, guitar pro and power tabs. Comprehensive tabs archive with over 800000 tabs! it's the only guitar website that has gear and cd reviews, music news, guest columns, guitar and bass lessons and tabs in one place!

Songsterr is a guitar tab site, but with a big difference. Each song tablatures is displayed on a flash-based online player which plays the song as you read through it so that you can hear the timing and phrasing of the entire song. Songsterr tab player uses very realistic guitar sounds. With close to 90,000 songs (500,000 tab tracks) in the Songsterr archive, you could easily spend the rest of your life learning new material! Songs are arranged not only by artists - and you will find almost everyone in there, but also by level (beginner, intermediate and advanced) as well as by genre.

Jammit is an incredible website where you can find very accurate song tabs and then play along the original backing tracks.

You can also find sites where you can search song tabs across various websites: