CoreCodex is a free online automated code judging site that gives you a range of problems to solve using a range of programming languages and techniques. Best of all: theres nothing to buy, install, or download. Find a programming challenge you find interesting and try to solve it. Your solution earns you points, can get you achievements, and if you find a unique solution, will get you ranked amongst the best programmers from around the world!

Check out my video introduction on YouTube:

Feel free to register today and try out a challenge yourself! Just remember the site is in an early alpha release and is expected to be buggy.