There are some useful apps among the thousands of fart machines and "X Jump!" games. Some apps I use regularly include:
"SlowGerman (Podcast App)" - We listen to German podcasts every week in my German class, so this is especially useful when I don't have access to a computer and need to do so, or when I'm in class and we can't access the website because the school blocks it. (The school disapproves of the "Facebook" link on its homepage)
"LEO" - A German <> English Dictionary. Useful in German Class.
"AS3 Reference" - The complete AS3 Documentation. It's useful when I feel like being especially nerdy or when I'm programming without access to Flash itself.
"TCT Lite" - A periodic table. Useful in Chemistry.
"EpicWin" - Allows me to feel accomplished after completing trivial goals that I set for myself.
"More Toast!" - What's wrong with a little virtual toast on the go? stfu it's hilarious
"Convertbot" - Converts currency, measurements, etc.