How to organize so many books...

I have about 16 bins full of chapter books. For most of my teaching career my books have been organized by AR book level. then two years ago our school started utilizing Lexile levels as well so, that is how I organized my library. But, after reading the The Book Whisperer I realized I needed to once again reorganize my library. And this time I want catalog my books so I will know what I have and where the holes in my collection are so that I can increase the quality of my collection. For this reason, I am excited to start using GuruLib. Yes, I already have a Goodreads account for my home collection. But, I have found that GuruLib is kid friendly. I have the students log onto our classroom catalog when needed. And, they can look at our catalog from anywhere they have internet access, in case they want to look for a book at night before returning to school each day. You can check out a teacher's sample here.

How do you keep track of the books in your library??