Kindle, eBooks, Others
I think the Kindle is cool. Easy to use and very easy to publish to. Lots of options in this arena though. Sony has a player as do several of the major book sellers. Of course, formats are different and we're all looking to see who will win the new betamax/VHS war here. And there are some organizations that will adapt content for any/all of these platforms. But when we look at all the options, it seems like the EPUB (http://wiki.mobileread.com/wiki/EPub) format has the best coverage of all.
http://labs.oreilly.com/2009/03/epub-resources-and-guides.html