Yeah, there are also gift cards you can buy at the grocery store (for a $5 activation fee!), but I've actually found that a lot of merchants don't accept them -

Yeah, there are also gift cards you can buy at the grocery store (for a $5 activation fee!), but I've actually found that a lot of merchants don't accept them - they have some way of telling which credit cards are "unlimited" and which are gift cards and just rejecting the gift cards as "suspected fraud".