It's back, O'Reilly's periodic (twice yearly?) 60% off sale on *all* e-books and vids (but not print books). You have to spend $100 (US$) to get the 60%, otherwise it's only 50%. Based on past experience they never go cheaper than 60% off.

I'm still waiting for blow-out deals on print, but they never come...

http://shop.oreilly.com/category/deals/cyber-monday.do

Ends Dec 1, 5am PT.