Topaz Labs has a new holiday sale: 25% off on all products (get an extra 15% off with code RUMORS15)
Skylum has new holiday offers (use coupon code PHOTORUMORS):
All DxO software products are currently up to 30% off until the end of December - use coupon code HOLIDAYDXO.
You can also get 10% off all ON1 products with code NIKONRUMORS.