I've just learnt (well I'm still learning) about writing GUI's in Perl using Tk. It's so damn flexible it shouldn't be allowed, I mean you can embed GUI into webpages and use it's really easy callback system to do, well just about anything.
Perl/Tk's best features are definitely revealed when writing local GUI programs though.
I really recommend anyone who hasn't already done so to go to
http://www.activestate.com, choose products from the top menu, and grab a copy of ActivePerl (definitely easiest to setup if you want the HTML/Perl as well). It comes with most modules installed which I why I chose it (I had trouble getting the Tk modules installed under Linux
).
Very neat little language, I can see I'm going to use this for a loooooong time
*edit*
ActivePerl is free BTW