There's a bunch of companies already in this space. Taleo is the dominant player and is used by most of the Fortune 100 companies, Kenexa is their main competitor. Although both are aimed at the enterprise.

There might be room for a competitor targeting SME rather than the enterprise though.

There have been a few startups in this space as well, catchthebest.com which was in this area seems to have deadpooled, so it might be worth making contact with the founder and seeing why it failed.