Practice Your Python and Java Coding at CodingBat.com
It may not be the most beautiful website out there, but it sure does get the job done. CodingBat.com is my favorite site to improve my Python coding skills through creating algorithms to solve problems. I love how it shoes how successful your algorithm is against all the expected outcomes, so you know when you're getting close and you can fine-tune things from there.
Here are 3 algorithms I solved there today; I love solving these: