I'm highly skeptical of design by committee software. Most open source soft is not done this way. Please form some kind of a structure on how to incorporate features and how to prioritize them and WHO decides what goes in. Popular votes might not be the best indicator...
You're dead right about design by committee -- the idea with microPledge is more like "funding by committee". Except that it's not a commmittee, it's a group of loosely-knit pledgers. They'll have their say in the project, but the design will still largely be done by the developer.
That said, very good point about some kind of way to prioritise and structure how and when features are included. We're thinking about it, and have a few ideas.
Shared interest is sufficient for a lot of projects (e.g. format converters, small plugins, bug fixes, performance improvements, support for a certain standard/protocol, driver support, port to another platform, etc.)
It wouldn't work for a full-featured 3D modeler or a video game, of course.
