Email: Whether it's the schools or a personal account, I check them a time or two depending on if I'm expecting something. Can add up to an hour.
Time Killers: A folder of sites that can include random pictures, jokes, comics, and humor. Depending on the day I can spend several hours back and fourth through several of these faithful sites...
Ebay/Part Stores: I've got an old car that needs restored, so I look through the online cataloguefor parts I might think I need. Depending on the item, some sites offer a better price. Depending on the week I could spend a hour just looking through interior pieces that I may or may not want to replace.