I have a handy donation hint that have served me well:
- Stack them against a wall with the spines up, and take some photos. Just fit as many as you can comfortably identify from the photo, then go to the next group.
- I've also taken the time to check the ISBN with Amazon for used prices on some of the more expensive textbooks and references that I've donated. It helps justify the deduction in case the tax man comes calling.
That way, you have both a record of the titles you used to have, and also evidence that you actually donated $85,000 of books in a year when you only made $65,000, in case the IRS has questions.