I do a lot of things.
1) Read and post on forums. A variety of forums.
2) Watch videos from a variety of sites
3) Video editing with Final Cut Studio
4) Play games through crappy Windows Vista
5) Play emulated games in Mac and/or Windows
6) Prepare lesson plans for my classes
7) Shop online
8) Keep in touch with people through Skype and e-mail
9) Assist with my studies (Japanese/Spanish)
And more. If you're bored of sitting at your computer, the answer is probably not finding new computer tasks, but getting away from your computer and doing other things.
Consider joining a sports team, take up weight-lifting, start a new hobby like photography, hook up with friends you haven't seen in a while, or start reading some books.