Resources: Programming Puzzles

Sites with Programming Puzzles:

Project EulerThe BEST source of programming puzzles on the Net.
Python ChallengeAlthough specializing in Python, these problems can be solved in any language.
Top CoderHundreds of problems from past competitions.
gowrikumar.comProblems showcasing the unique complexities of the C programming language.
Six RevisionsTen sites where puzzles can be found.