Hackerrank! I am currently taking an Algorithms course at Uni and I have found HackerRank's questions to be a great way to practice your coding skills. It can also help you out for recruiting.
3 karma · joined December 8, 2012
Also doesn't Linkedin already do this. They have a search engine you can use to filter out applicants based on school, past experience and location. I also believe they released a lite version to make it more affordable.
Some startups you should look at if you're interested in this space: Hired.com, Whitetruffle and Wayup.com (they introduced a way for companies to post requirements and get paid per qualifed applicant)