A participate-to-view web-app that would allow collection of comparative information about various systems/products.
I love and hate Mashable lists that tell you what the top 100 wikis are. I want something that gives me up-to-date comparisons. So here would be the workflow: I come to the system seeking information about wiki applications. I am asked a single question – I answer that question and am given answers that were given by other people. The question could be: which system do you like better based on functionality: pbwiki or wikispaces? I look into the systems, answer the question, and then get to see how other people compared 100 other wikis to each other, two systems at a time.