What are some good math contests online?

Answer 1

At what scholastic level?

I found the following "directory of math contests":

http://www.bcpl.net/~lmoskowi/math.html

There are lots more mentioned on Google, of course:

http://www.google.com/search?hl=en&safe=off&rls=DELA%2CDELA%3A2005-51%2CDELA%3Aen&q=math+contests

The one that seems to be the biggest deal on my college campus is the Putnam competition:

http://math.scu.edu/putnam/