Ok, this might not be news to everyone here, but I gave up playing WoW a while back, so I haven't kept up with what's going on over at Blizzard. However, it seems like you can now get a Visa card with one of 13 designs that are on offer.
You also get a months free game time when you use the card for the first time and for every 1,500 points you collect (the catch here is that it's one point per $1 spent) you also get a months free game time. You need to have a WoW account to sign up for the credit card and it seems to be for US citizens only.
Click here to see the designs and to find out more.