The most impressive Ðapp I have seen so far (found via stateofthedapps.com) is leeroy.io, a short message service using Ethereum for signing up, posting, following etc. (micropayments for interactions, in some way).

Makes a lot of sense if you think about how incentives could change because there is a perceptible cost involved. Then again, of course, it’s all about the money. Anyway, we will mainly see gambling and betting Ðapps in the long run… betcha.