Plus there's the established Code Kata resources. The CodeKata page, Mark Needham's blog posting on code-kata, Rizky Farhan's Collection of Software Projects, jp.hamilton's Code Kata Resources. The Coding Dojo page (which suffers from showing no usable URL's -- what a mistake.)
I've done a few (63) Project Euler problems (I got stumped by problem 69). Another 37 and I'd be at level 3.
The question isn't "where are the problems?" The question is "Are these good Code Kata problems?"