Interesting books I've found helpful:
Ones I like:
1. Digital Astrophotography (Stefan Seip) (Excellent primer on digital imaging): http://www.amazon.com/Digital-Astrophotography-Guide-Capturing-Cosmos/dp/1933952164/ref=sr_1_1?ie=UTF8&qid=1325364181&sr=8-1
2. Night Watch (Terence Dickinson) (good general book on Astronomy as a whole): http://www.amazon.com/NightWatch-Practical-Guide-Viewing-Universe/dp/155407147X/ref=sr_1_4?ie=UTF8&qid=1325364235&sr=8-4
3. Backyard Astronomer's Guide (Terence Dickinson and Alan Dyer) (more detailed book by Night Watch Authors includes a section on digital imaging): http://www.amazon.com/Backyard-Astronomers-Guide-Terence-Dickinson/dp/1554073448/ref=sr_1_1?s=books&ie=UTF8&qid=1325364282&sr=1-1
4. Merlin's Tour of the Universe (Neil De Grasse Tyson) http://www.amazon.com/gp/product/0231069243/ref=oh_o04_s00_i00_details This book by renowned astrophysicist Dr. Tyson is a fun read. I purports to be written by Merlin who lives on the planet "Omniscia" in the Andromeda Galaxy. These are answers to Qs from readers of Dr. Tyson's column in a newspaper. Moms & Dads this is a great tool for reading occasionally in Q&A format to kids so they learn about science! (I use it myself with students). There is a second book in the series that I'll post when I've read it.
Links are all Amazon as you can buy used versions relatively cheap. I'll add to these as I think of more (or read more!)