Great topic. There are a bunch of haters in this thread, but a game is a great way to learn a lot about Tk. I wrote a tetris clone in it about a year ago called Spew. It's like tetris, except as the levels increase the board spins around and zooms in and out. Give it a try (source and compiled windows exe included).

Download Spew Here

I use perl2exe to compile the program into an executable file. As far as books go, I usually use information online although I found O'Reilly's "Learning Perl/Tk" to be helpful when I started out. Hope this helps!