Jumping in here
Geoip'ing and/or adjusting US/EU prices as not to piss off the user are good ideas.
Phone-based payment solutions are really strong in Europe. Whether it's pay-per-minute, pay-per-password, or SMS/microbilling, Europeans are often more comfortable paying this way. We pay out $1.48 for each minute that a UK user spends on your site. pretty damn profitable!
thought I'd throw that in the mix
