Don't go on this site if you're a procrastinator, it'll keep you for hours. It has games, trivia, puzzles, everything you need to keep you entertained.
A music site that allows you to pick your mood and it plays music that will suite it. A cool concept, nice to have on while writing papers...pretty fun to mess around with, too. Finds good music most of the time.
A website for teenagers to submit any type of writing or artwork. Pretty cool to look at even if you're not a teen anymore. Could be useful for future teachers