BYEBK
I got this in an email, I don't know if it's a one-off discount code or if it can be reused:
Enter code "BYEBK" in the O'Reilly cart.
Buy 1 Ebook, Get 1 Free
Buy 2 Ebooks, Get 2 Free
Buy 3 Ebooks, Get 3 Free
Download in 4 DRM-free formats: PDF, .epub, Kindle-compatible .mobi, and Android .apk
thought for a moment this was the rightwing wingnut Bill OReilly off the FoxNews channel!