I don't think that cash prizes would be a good idea, whether small or big.
This is a site for leisure time, for communicating with friends, for sharing ideas, information, talking about interests, worries, pains and happiness, for learning without stress, for laughing and sharing emotions, for contributing to moments of inspiration and of fun.
"Mass production" would only spoil this site.
And a good laugh (not a forced one) and kindness may seem to be little awards, but real feelings and friendship cannot be bought with money!