A game jam is where lots of game developers get together (either in person or via the internet) and all make games at the same time. Quite often the time limit will be very short, many lasting only 48 hours and some being even shorter! There can be prizes, but more often than not we do it just for fun.
These are the game jams I've taken part in and will be taking part in in the near future:
Note: This page is still being converted to the new system and not all games are available yet.