I'm inclined to think mathoverflow will be more researchy in character than these other sites, which have a math competition tilt. (which means mathoverflow has

I'm inclined to think mathoverflow will be more researchy in character than these other sites, which have a math competition tilt. (which means mathoverflow has won me over) Also, there are some pretty high powered math problem solvers who are active on math overflow, eg reid barton: http://en.wikipedia.org/wiki/Reid_W._Barton http://en.wikipedia.org/wiki/Reid_W._Barton (one of the top performers in the history of the putnam among other things)