There's a paper out in ProcSoc B about aggressive mimicary, a very devious way to hunt by pretending to be prey or a mate, and then gobbling the hapless critter that comes to investigate.
Here are some of my favourites!
Photuris fireflies

Female fireflies attract males with a precise courtship signal. I don't know whether to be impressed or sickened, but the guys rather deviously waggle their bum to look like females, luring males in, then scoff them. "Look, its Dave! Mind you, I am hungry..." (proceeds to waggle bum like girl).