Hm, I wonder if the American version of yahoo wallet would work? http://wallet.yahoo.com/

The site definitely seems to be set up for the foreign market, the search only lets you view auctions that ship worldwide.

Hahaha! I felt like such an idiot trying to register today, and THEN reading this post. I couldn't get the phone number to stick. It took me like an hour of number configurations. Then, once I was successful, the form deferred to 'cannot accept credit card...' I agree with some folks above, there really isn't much point to registering, as most everything us SB'ers end up bidding on far exceeds 4999yen!