Chris Sells WTL Articles
Chris Sells has made his two WTL papers (WTL Makes UI Programming a Joy) available for download from his site after they were removed from DevelopMentor's. Both are in zip format: Part 1: The Basics and Part 2: The Bells and Whistles. These are excellent introductions to Microsoft's WTL.
While you're getting those it's worth browsing the rest of Chris' writings.