MobiPocket
I would expect MobiPocket (at http://www.mobipocket.com) to easily be the best ebook format. After all, it's aided by one of the best DRM (Digital Rights Management) schemes around. However, it seems there's something that doesn't quite feel right about MobiPocket, and it's hard to put my finger on what it is. There's a version of their reader for just about every device around, their DRM solution is user friendly, their pricing is reasonable, their selection is not vast but it's unique and varied, and their format should be a poster child for the Open eBook Format (OEB at http://www.openebook.com).

All of these things should make a really killer program and format; but I'm just not in love with it. Nevertheless, because of its general acceptance by fans and readers, speculative fiction ebooks are usually more available in electronic format than other genres, as is the case with MobiPocket. Despite my personal reservations, I think that MobiPocket is well worth checking out.

Baen
Of all the big name Speculative Fiction publishers, Baen (at http://www.baen.com) has taken one of the best approaches to ebooks that I've seen so far. Baen primarily publishes contemporary science fiction/fantasy in paper formats. When ebooks presented themselves, Baen decided to try a completely radical way of using ebooks as part of their marketing department. They offer the first book or two in a series for free, downloadable in multiple file formats that are free of restrictive copy protection. If you want to read the rest of the series, you can either buy the print copy of the book or you can join a Web-subscription that gives you Baen books in electronic format for some regular monthly fee. If you're interested in books from the likes of David Drake, David Webber, and Eric Flint, Baen is well worth your while to check out.

Jeff Recommends
Jeff Kirvin, noted mobile tech pundit, writer, and ebook champion, has a collection of fine ebooks on his Writing on your Palm Web site (at http://www.writingonyourpalm.net). All of Jeff's recommendations (at http://www.writingonyourpalm.net/recommends.htm) are formatted in almost flawless Open eBook format XML, which is backwards compatible with standard HTML. All the books are free and come with instructions for converting the books into a format for reading on your PDA.

Some of the books mirror Jeff's interests (which include Speculative Fiction), and others are classic works that are worth having in your ebook collection regardless of your genre interests. While most of these books can be found through other sources, Jeff's little library is well formatted, free, and easily accessible. What more can you ask for?

MemoWare
MemoWare (at http://www.memoware.com) is the largest receptacle for documents formatted for handheld computers. They have the largest collection of public domain and other documents for the mobile reader, primarily in PalmDOC format. All of the books are free and in unrestricted formats that can be read with--in most cases--regular DOC readers. If you're looking for a book that is either in the public domain or is being freely distributed, it's worth your while to check out MemoWare. Because there isn't a whole lot of contemporary literature entering the public domain right now, and there never were copious amounts of speculative fiction in the public domain, MemoWare's speculative fiction section is decisively lackluster in comparison to the other genres. However, for a quality free service, it's hard to really complain.