PCHPoints and LuckyPoints both offer Webcertificates (which are Mastercard). However, the points/$ for Webbies is higher than other prizes. I prefer the $25 Supercertificates which can be exchanged for RFC GCs.
Memolink offers Webbies but I have yet to see one. I cashed out over the summer and I'm still waiting. I've dumped this program and I would not recommend it to anyone.
CreationsRewards offers both Disney Dollars and Webbies. They also offer cash via bank check or PayPal. Chris is very good at customer service. This program is a slow earner if you don't shop thru them.
ClicktotheMagic offers Disney Dollars. Lots of search banners to click on and its pretty easy to do. Points add up slowly but Bonnie is good at crediting points for shopping and signups. The prizes go out very quickly once you've redeemed.