Other related projects/sites/products include Blueberrytree[1], Trollim[2], CodeYourIdea[3], HappyJobSearch[4], OneDayOneJob[5], and the aforementioned iSeekMikeCode[6].
I'd have to be at my home desktop and check my history for a good list of links, but I got to use a handful of competitors when I was looking for work a couple months ago. I'd have to try this one out to be sure, but the extra polish plus the ability to use the interviewee's own IDE could be huge advantages.
Wow you can create your own challenges? That's awesome. I've seen some sites like this before, but they usually have a predetermined amount of algorithms.
I always wanted to make my own challenges that would have to be automatically solved by potential candidates, and here it is! Glad someone else did this already.