I previously founded and sold a VC-backed marketplace for short-term contract programming work. However, I think any of the marketplace-style business models are flawed because they have to be so controlling to maintain their cut of the revenue.
I believe we need a simple job board for part-time, freelance software work. No long process to apply. No need to rate your coworkers to get paid. No subscriptions or revshare. Just a lightweight job board with a great email and good matching.