Thanks spaceman.
There's a lot of confusion (everywhere, not just here) as to what exactly the offers require. There are three offers I personally would do, as two are free and the other is useful. Here goes trying to sway you.
1. Stamps.com. I've heard that this charges $1.50 as a verification fee to make sure the card isn't maxed out. I imagine this is refunded, but I cannot say as the prepaid card I used for verification only had $0.45 on it and was rejected. This can be canceled a couple days after receiving credit, and the credit just stays there.
2. GameFly. Like Netflix but with video games. This or #3 is going to be the offer I do (I need to check if I need #3 first). It is a 10-day free trial of GameFly. You must queue a game, credit card isn't charged, and credit will remain on your YourPS34free account if you cancel your GameFly membership over the phone on the 8th or 9th day. I have actually been wanting to register at GameFly for a while so I personally wouldn't cancel...
3. 00InkJets. Order $30+ or $35+ (there's two similar ink sites, one needs 30+ and the other is 35+, don't remember which is which) worth of printer ink and you get credit. I have looked and the ink certainly is quite a bit cheaper than my local Staples.
4. Keen. This isn't one I would suggest unless it's a boring, rainy day and you're willing to spend $4.00 on a reading from a phone psychic. It probably would be fun to do over speaker-phone at a party or something, I guess.