The guy who helped bring you Crate, a dead simple file-sharing service, are now testing something called Gumroad, a way to ask folks to pay for downloads. The site is very basic – you enter a URL, a price, and share the link. Users are asked for a credit card number (don’t buy that, it’s just this) to buy the item and sellers pay 5% plus 30 cents for each sale. The system is aimed at ad hoc sales