I just finished reading an awesome SF book called Ventus, by Karl Shroeder. I downloaded it for free from his website and put in on my Palm handheld. For days it went everwhere with me and I snatched moments to read more every chance I got.
I’m not much of a reviewer, so I’ll just say that if you like hard SF with a touch of fantasy (strange combination, works amazingly well!), then you should like this book. And since you can try if for free, there’s no reason not to. :)