tl;dr : If you are looking for fun ways of practicing your algo skills, and might be interviewing soon, then read on.
We have made InterviewBit ( http://www.interviewbit.com/?invite_code=spoj158 ) which is a fun way to prepare for interviews and get really good at algorithms in the process. The problems have been categorized into topics and then micro-concepts within topics. Each problems have hints and editorials with them.
Some more feature details here : http://www.quora.com/How-do-I-get-a-job-at-Facebook-or-Google-in-6-months/answer/Anshuman-Singh11
Do give it a try, and let us know how we can make it better for you.