Books
Manning published Python and Tkinter Programming on dead-trees in 2000 for John_Grayson.
An_Introduction_to_Tkinter (Fredrik Lundh)
Tkinter: GUI Programming with Python at the New Mexico Tech. Computer Centre.
O'Reilly published Programming Python in 2001 for Mark Lutz. Now in its 4th edition, see Mark's site.
O'Reilly published Python in a Nutshell in 2003 for Alex Martelli. This book has one good chapter (16) on GUI development with Tkinter.Martelli's site.
Others include:
- Python 2.6 Graphics Cookbook
- Python Power! The Comprehensive Guide.