You can check out Anki[1]. Apart from the initial setup, you won't have to worry about taking care of the web server.

I create separate decks for different fields and then only if necessary do I create subdecks. I also tag all the cards that I create and make sure to spend a lot of time to ensure that it's made and tagged properly. So, whenever I learn something new and I believe at that point of time that it's worth remembering, I create a card for that.

[1]: http://ankiweb.net/