I guess I technically don't have a TBR list except for my weekly indie book reviews.
For my not-blogging reading, I only buy books when I'm about to read them. All my free + sample ebooks are shelved in collections, and I pull them out of the collection when I'm ready to read them (and of course, purchase the full one if I only have the sample). My paper books are in stacks around the house, and whatever is about to read next is on top of the stack
I have a "Books I Want" list that's a 10 page long word document. I have it sorted by Fiction, Non-fiction, Online-only, etc. The first page is dedicated to books I'm serious about reading soon, especially if I can borrow them from the library, so I also include the library call number on the list. It's handy because I can just upload the .doc to my Kindle and I can take the Kindle to the library. And if none of my priority reads are available at the library, I can skim through the other pages and pick something else. No paper or pens required.
For my blogging reading, I've committed to reviewing one indie book a week, so I let authors know ahead of time when they can expect to get a review... is why I tend to finish more indie books these days. It's 6-8 books long maximum, because while I can predict what I'll crave to read in a month's time, I may have different interests in three months. I keep track of what to read next with the review schedule on my blog
http://fridafantastic.wordpress.com/...view-schedule/
My indie Want to Read list is organized by tags on Gmail since authors email me book submissions, and each week one of those books get into the review schedule.