Fictionwise eBooks - and this is my favorite eBook dealer at the moment, delivers various formats and offers useful search functions also by format. Also there are the LRF files best suited for the Sony. Nice: there are also quite current titles and with their software you can also read the books on the iPhone. Unfortunately, many publishers are being difficult, so for example you can only get the books by Neal Stephenson in DRM-crippled formats, none of which are compatible with the Sony.