The most "legitimate" use for bitcoin and its friends is transferring funds electronically with people that others don't want you transferring funds with (e.g, avoiding payment processors, laws, etc).
However, it remains to be seen if cryptocurrency could survive doing only that (e.g., without speculators) - because if there's no speculation how do you unload the currency? Only to others wishing to do the same. It's possible, but will it work out?