Hello,
i got another suggestion, this time about the challenge overview:
It would be great to be able just to display unsolved challs and to order them by votes (like "order by overall vote","order by difficulty") or number of people of solved it.

mxn

Yeah I like that idea. When I am stuck for a challenge to try next I download into Excel and sort by stats. At the moment I am trying all the challs that have had 50+ people solve (as hopefully they should be a little easier)