Diane Duane and Peter Morwood's books are 66% off today.
code: BLACKCYBER gives a 66% discount of anything at their
ebook store.
The discount code isn't entered or applied until after you come back from the paypal payment screen - there are instructions and screenshots in a link on the left. It's a bit scary, but the discount does get done before you click the final Buy Now button at their web site.