Selling some sort of lossless format is a must
I'm still buying the majority of my music on CD and ripping in order to get high quality files. Luckily, iTunes converts to AAC on the fly for my Nano and iPhone but I don't want to listen to lossy music files at home. Not sure how much revenue this would bring but it would certainly get folks like me to make more purchases there. Maybe I'm the only "dinosaur" out there who prefers high quality files but I doubt it. The services that sell these now are nowhere near as slick as iTunes with scant offerings in their catalog which makes ripping after an Amazon CD purchase still the best option.