Pavement Runner has a very nice assembly of Cyber Monday RUNNER deals.
In fact, I used the Inside Trail Racing discount code to save on next years Folsom 50K. Saved a nice $10 off.
Another sorta discount is the $5 deal on New York Marathon lottery registration. Yeah, kinda dumb that you have to spend $5 for a lottery chance but hey racing isn't cheap. If you have been turned down three years in a row or something like that then you get guaranteed entry for 2014 - that is better deal.