I tested out movie rental service Quickflix earlier this year by taking advantage of a bargain-priced trial offer. If you want to give it a go with even less risk, there's a six-week free trial running at the moment.
The six-week option comes via DealsDirect, and extends the existing 2-week free trial. You need to make sure you cancel your subscription before the trial expires in order not to get slugged with an unexpected bill (you have to provide credit card details as part of the sign-up process). I didn't have any trouble doing this, but some readers did report difficulties, so don't leave it to the very last minute if you test the service but decide it's not for you.