I'm just sorting mine by Author's name (last, first) in folders, with sub-folders for series listings. Back when I had enough shelf space, I did something similar, alphabetically by Author's last name, then by title -- except for series, of course.
I've got a second set of these for texts I'm still in the process of, um, processing, so I can tell where I am. And I recently added a "Reading Shelf" folder so that I have a place to keep track of the half-dozen or so I plan to read 'next.'
It's all basically modeled after how I handle my books in the 'real' world, so it works well for me, 'cause I'm not really doing anything different.
I'm presently keeping the lot on a flash drive, which means I have access to them wherever I am, which is handy for all sorts of reasons.
