I recently found this learning tool called "Anki."
It's a flashcard system which is nothing new... but what it does that's fantastic is that it times out the recurrence of the cards in order to increase memory by "spaced repetition.".
I know there are a lot of students here and I cannot recommend this enough. There are a bunch of card sets for various subjects already - but you can very eaily make your own as well.
A spaced repetition system is a great thing because it addresses how we learn. (Mneumonics is another way and someday I should blog about that.)
So - whatever it is your trying to learn - a language, math, programming, legal terms, accounting terminology, greek gods, whatever - try this out and I don't think you'll be disappointed.
Oh yeah, and it's free. And it works on mac, pc, even iphone and windows mobile..
http://ichi2.net/anki/index.html
Be sure to watch the intro to understand how it works (very simple)
http://ichi2.net/anki/screencast1.html
Enjoy learning!