My suggestions (off the top of my head which might be missing a few that others can throw in):
Gamefly ~$10, 30 day trial, cancel online
Netflix ~$8, 30 day trial, cancel online
eMusic ~12, 30 day trial, cancel online (make sure you check your card, I've had that situation before, but then they sent me a confirmation e-mail eventually)
Savings Circle ~$5, but get refund once cancelled, 30 day trial, cancel online
Profinity ~$3, 14 day trial, call to cancel (if you call around 7PM, you might get lucky and be able to cancel via automated system, otherwise you'll deal with a live person which can be annoying)