I do not toe the line and keep perfect records, Joan, but I do have lists on my WORD, saved by author's name, of those I have read so that I can refer to these to check whether or not I have read a book that someone mentions or I read something about or see an advertisement for. I also print these out occasionally and keep in a real file in my real filing cabinets under the title BOOKS. Hey, there's an easy one!
Finally, I keep a WISH LIST offered by Barnes & Noble to its membership. Once upon a time I was much more rigidly organized, but now that we have computers and Google and I can write in "list DCI Banks books by Peter Robinson," for instance, and receive an instant and up to date listing IN ORDER. Life is good, and I find I am not nearly as obsessed by perfection in these matters as once I was!