I think something like what premchai21 mentioned would be quite good. I remember wishing I could ++ a few nodes around here.

I agree with TGI that there should not be an XP gain by the giver of the C! and since I would assume that the truly awesome nodes are infrequent, why not a set number a week? Imagine a C!-votebot going around trying to --C! the Elders.. yikes.

of course, even without the C!'s you could always /msg the author and tell them what you thought of their node. Having someone thank me for my thoughts is worth more to me than the XP.
-p