I'll do a lot of Twitter, Youtube, PokéCommunity, Tumblr, browsing Serebii and Bulbapedia, searching entertainment websites such as Entertainment Weekly, Skype, iTunes, and Photoshop. On a rare occasion, I'll pop in on Facebook for like a second or two.
If I'm really bored, then I'll go to places like OhNoTheyDidn't and just read comments (I really try not to do that) or I'll go browsing LiveJournal and DeviantArt looking for nice icons or background wallpaper to use at a future time because making my own graphics today is just too hard.