I'm reading the
Palladin of Shadows series from John Ringo, it's pretty good, though can be a little graphic as can all military scifi. Basically I enjoy reading most of the works that come from baen books, not to mention that in MS Reader format they are quite portable (especially with an 8Gb card in my PDA phone) not to mention free (The fifth imperium site has permission from baen to host the CDs, plus baen books make some titles available for free in the baen free library)
As soon as I sort out the last of the paperwork to get to the US permanently I am going to try to buy most of those books, as I do like the feel of paper in my hands when reading, but for sheer portability, ebooks work for me.
David Drake is another good author, 'The Far Side of the Stars' is a good read, available in audio book format
here (34 chapters to download as mp3 unfortunately) and
here in MS Reader, HTML, MobiPocket reader formats. (again, free)