I just spent five hours rearranging my giant CD book by:

1.) Road Trip Mixes
2.) MD, PA, WV, OH, IN
3.) IN, WI, MN
4.) SD, WY, CO
5.) NM, AZ, NV
6.) California!

There are also some other categories, like: Comedy/Spoken Word, Random Mixes, Random Albums, Movie/Musical Soundtracks, Classical, Natural Sounds

It took forever, but it looks great. Yay organization.