Whoo! 3rd time rejected! Getting rejected by YC definitely gets easier with time, and I have found it only motivates me further to keep going and prove them wrong.
Yup, 3rd time here too. This was our first time applying with TwoSides (http://www.twosides.co). No worries though, we should all keep plowin' along.
I think the 2 major things you can take away from being rejected multiple times are A) they really hate your idea, or B) what you're doing isn't "hot" among Silicon Valley investors right now. I have a feeling their choices depend greatly on what they think can get to a Series A funding round. So in either case it really doesn't invalidate what you're doing, and if you can at least get to ramen profitability, then it really doesn't matter what YC or anybody else thinks and you can keep chugging along.