Ask HN: Would You Use Opinionkarma.com? Why or Why not?

There have been various things I wanted an opinion on and my question doesn't usually get a lot of traction. I would like a site where I could help other people out with answers and opinions and get some kind karma I could spend. On this site for instance I have a pretty good Karma score but I can't do anything with it. what are your thoughts?

Are there sites like this already? Has this been tried before and failed?

Would I be wasting my time?