StumbleUpon is a really great way to lose several hours online. I can't tell you how many times I've realised two hours or so had passed after I hit the stumble button.
At work: news, cag, some gaming sites, check email
At school: news, schools career website, cag, gaming sites
At home: porn, youtube, cag, gaming sites, more porn
Email, CAG, new music, wiki, job postings now that I need something with more pay for less stress, rare YouTube account maintenance, vgreleases, Bioware Official Forums for laughs/to reaffirm how disconnected I am to the Mass Effect series now, etc. Every year I find less reasons to remain online for more than an hour.
I forgot to say I watch classic game rooms videos on youtube and my little pony friendship is magic. I also suggest for nostalgia watching the classic unsolved mysteries videos specifically the paranormal and ghost episodes.