Slinkset is maybe not an original idea (corank is pretty similar and was around first) but it's a good one and very well-implemented. You don't make money by being original. You make it by being good. Allowing people to start their own sites trivially (not counting some goofy domain issues I had, I think NHN took me 10 minutes or so to set up) is a good idea, and one that has been popular since before the first bubble.