The MacSanta site gives a 20% discount on software purchased from participating developers using the coupon code MACSANTA. Developers include Rogue Amoeba (Audio Hijack Pro), Flying Meat (VoodooPad), and Bare Bones Software (BBEdit), and Advenio (Mac Gourmet). There’s even an RSS Feed to keep you updated as more discounts become available.
There’s even a poem “A visit from MacSanta”.