Manning online bookstore. In theory they support credit card payments, but I guess they are not capable of handling 3D Secure protocol, so my attempt to pay with a credit card always fail with them. Every time I need to buy something from them I would create a temporary PayPal account (which I delete after the transaction :)
Wow, really? Never have actually encountered a site like that. So I can only assume it's rare enough such that it wouldn't be much of a hassle to just refuse to do purchase things from those websites.