Search around, it has been done before, and it failed. I think the reason they failed was it was too closely to kickstarter, I think if you built out the idea a bit more and some more features, instead of a direct copy.
Was just thinking about it, using sites like those as inspiration. This would be a fairly large project that would take me a while to do. I use be very active on prosper before they shut down lending money out because they don't have a license in my state.
Thinking about prosper, the site could be set up so you loan BTC to the person or biz, would receive monthly income. I don't think this will work since the value of bitcoins is very volatile, I could be wrong though.
A bitcoin kickstarter would be pretty cool, but this idea needs to be really be fleshed out with a full list of features and functionality before I start work on it.