I just wanted to let everyone here know that WWW-Card is really easy and works on Pokerstars (Haven't tried any other sites). You pay via a debit/credit card, and you have your virtual card # instantly, and it tells you that you can use it in 10 minutes. If you try to use it before 10 minutes on Stars, you get denied, but if you wait 10 mins, its approved.
The max you can load is like 200-300. You can do more than one. I think its like 2 every 24 hours or something. There is a fixed fee of $2.75 each.
They also accept giftcards.com prepaid visas (for those of you who bought them but then got screwed because they no longer allow gambling transactions.)
I've used them ~4 times, very fast and easy:
https://www.www-card.com/
(No, this isn't spam, and no, I do not work for them, nor am I an affiliate, just helping everyone out here).