Some of John Ringo's books can be found for
free download at the publisher's website. The stories are a tiny bit reminescent of Starship Troopers, but only in the vaguest of senses. They're military in nature, and a very good read.
My best method found for those books from Baen is to download in HTML format, and then use iSiloX to convert them over to iSilo format. The default iSilo3x format on Baens' site isn't ... the best. Of course you could also use any other e-book reader that supports HTML files.