I can't let this question go by without pointing out my own two science fiction (not fantasy) dragon novels,
Dragons in the Stars and
Dragon Rigger. They're both in ebook, multiformat. (They're in most of the ebook stores, but I recommend either fictionwise or webscription for DRM-free versions.) You can read the short story that the first book was based on,
"Though All the Mountains Lie Between," on my website for free.
My family also really enjoyed Patricia Wrede's series, which I believe started with Dealing with Dragons. And Jane Yolen wrote a good YA trilogy, the Pit Dragon series.