* My mom, who wants a free alternative to MS Word that works well on Windows and is less intimidating than OO (and more powerful than Google Docs)
* People who saw an OSS tool running on their friend's Linux and want a port to their platform
* People who run existing closed-source software that they want to add a feature to, but can't
* People like me who code, but are too busy to learn to hack Platform X just to get Feature Y
I was a long-time mp user. Unfortunately they are no longer operating. As I understand it, their model was more focused on funding (mostly closed) software in an open way. Of course, it's difficult to convince closed-source people that community funding is a good idea, and I think that was one of several challenges they faced before shutting down.
Our focus is completely different. We want to connect people with OSS. A large part of that is money (because money is a strong attractive force). We talk about it a lot, because people start listening when you tell them they're going to get paid. But there are other problems too--search (how do people find OSS projects?), developer time (I have a week--what do I work on?). These problems are far out of bounds of micropledge or other bounty or funding systems.