Procrastination
Here are the things that are SO much more fun than studying/outlining/practice exams:
Sudoku - I won't tell you how long it takes me to solve the "easy" puzzles, but they are addicting.
Lots and lots of blogs
Distributed Proofreaders - This is the site that provides proofreading and formatting for the books being posted on Project Gutenberg. So for all of you who can't get enough of proofreading, this is the place for you.
Hoyle Solitaire/Card Games
Sims 2