Good, article, but let's be honest here. We all know this is the real list:
1. Reddit/HN/Digg/etc.
2. Facebook (move to #1 if you play Farmville or are female)
3. Steam/xbox/playstation/WOW/Dwarf Fortress
4. Checking Email
5. Watching videos/movies/tv
6. Doing something pointless on your phone
7. Etc. Choose your own time-waster