Hi Christian. Great site, just joined, am enjoying it.
I got a few suggestions I'd like to throw at you, I think might improve the experience even more:
* Add competition results to the profile graph (currently only tests are included);
* Have language specific graphs (currently mixed afaik);
* Have stats further back (analyze longer term improvement etc.)
* Add community features, like comments on competitions (competitors only) and profile pages;
Last probably has most impact..