Not sure which e-book format to pick?

EPUB: open e-book standard, works with Sony Reader, B&N Nook, Stanza, FBReader

MOBI: works with Amazon Kindle, Mobipocket

PDB: works with Palm, eReader

HTML: for online reading in your web browswer - Firefox, IE, Safari, Chrome, Opera

PDF: best for printing

TXT: when all else fails