For a few years now, a collection of developers have put some of the best iOS and Mac productivity apps on sale at AppSanta. They're back this year with a full menu of great apps to choose from. I bought several that I didn't already own this morning. Some of my favorites this year are:

Drafts 4
PCalc for Mac and iOS
Deliveries for Package Tracking
TextExpander touch (The keyboard, by the way, is much improved.)
Ember for Mac and iOS
Screens for Mac and iOS

There are even more listed at AppSanta.