@Synaptic: Two questions...

1) Does your proposal result in a limited number of ?coins being produced?

2) Does your proposal attempt to distribute ?coins at a constant rate, or a variable rate? And if variable, what determines the rate of distribution?

-------------------------

@Minsc: I don't see how you're going to avoid what you're perceiving as a problem.

Mining needs to be based on something. In the case of Bitcoin, it's based on computational power. Whatever resource you propose to replace computational power, is going to be more available to those with more wealth.

Even if mining required answering Captchas, who will be more successful at this: someone trying to mine alone as a hobby, or someone who can hire a roomful of folks to do it for him? Greater wealth always means greater power. There's no way to avoid this in the physical realm.