During the weekend and next monday (from 27 to 30 November) many products at BlenderMarket will come with a 25% discount. Of course I will participate in that sale as well, so if you were thinking about purchasing either WeightLifter or Space Tree Pro, now is your chance to get an even better deal :-)
Now I wouldn't want to exclude my Open Shading Language for Blender E-book from the fun so even though it is not marketed by BlenderMarket it will carry the same 25% discount during the Black Friday / Cyber Monday weekend.
Get it on Smashwords and enter the coupon code
QP54E on checkout.