Someone sent me this link
http://fivetriangles.blogspot.com/
It contains challenging geometry problems for middle and high school level. Unfortunately I didn't see solutions!
This blog for teachers contains an unordered series of problems
for middle and junior high school students. The problems are not
intended to be ``clever'', but rather require only a knowledge of
already-learned basic mathematics principles, applied in a more
sophisticated manner than for the problems found in a typical textbook.
