IGN Prime is currently being open for abuse, as if you sign up, even on their free trial, you can get a lifetime 15% discount on GamersGate
, and there are currently giving away a couple of free Steam games too to Prime people.
Simply sign up here
. Although you have to give them your payment details, you can simply go and turn off auto-renew here
Of course it might be worth bearing in mind that all of Carpe Fulgur's localised titles are on GamersGate if you can't think of any games you might buy from there.