We actually did exactly what you're asking here a few weeks ago and applied to YC this round with it. http://www.exipe.com http://www.exipe.com We built it in

We actually did exactly what you're asking here a few weeks ago and applied to YC this round with it. http://www.exipe.com http://www.exipe.com We built it in node.js and MongoDB. While node and mongo are young projects we have found them very stable and extremely fast. (we noticed a lot of problems reddit had with scaling and we were interested in the stack) Our decision to build Exipe in node/mongo has been a bit controversial but we've found no problems thus far with it ... ~2 weeks out with slowly growing traffic. Check out a few of my latest blog posts here about the experience: http://www.travisglines.com http://www.travisglines.com