I use and like 2CheckOut. Personally, I hate PayPal and would never consider doing business with them. I found 2CO when I was looking for an alternate processor that didnt want my first born.
They accept people worldwide, have a "request payment" feature for auctions, offer an ATM card for international clients so you can suck the money out of an ATM and they'll wire you or send you a check. They also support foreign currency for your customers, which may be of intrest to some of them.
http://www.2checkout.com/cgi-bin/aff.2c?affid=35199