Oreilly is the way to go here:
Matering Perl/Tk
I love all their books. My only complaint though, is I hate building GUI's manually! Its way too much code, and takes forever. I'd like to know if you have a Visual GUI designer that you use for Perl/Tk. I have tried Activestate's Komodo 3.0, but I don't like it. Since I program mostly in windows(I know, Iknow) I have actually taken to .Net. I got the Perl Dev kit and visual Perl from ActiveState and using C#,Visual Studio, and a book called Programming PERL in the .Net Environment by Yevgeny Menaker & company I have been having a blast.
Since everything is an object in .Net I simply draw a GUI ina C# project and make it inheritable. Then using the specialized PerlNet syntax I create a Perl object and code all of the methods,properties and event handlers in PERL! Its great. Of course this does not make for crossplatform code, but it does work, and works quite well for what I need.