Oh, it's that guy that hates everything.<p>ChangeTip is <i>cool</i>. It is a Bitcoin killer app. Like it or not, <i>giving</i> tips, even to people who don't need them, is fun. And for every person who is tipped who may not want or need it, I've seen some kid who is quite happy as they realise they've just been gifted something worth a few dollars. And then their journey into Bitcoin begins as they try to figure out how to actually spend it.