I solved that by buying an embarrassing number of Kindles -- I just leave one dedicated to a book as I'm reading it, and keep it in a convenient and obvious location. I have audiobooks on my iphone for the gym (using the Audible app), audiobooks on mp3 SD cards for my car, a Kindle by the bed, and have a DX, iPad, second computer for reading things which change more frequently.

4-6 Kindles and everything electronic is still a lot easier for me than storing books.