in reply to Other languages besides perl
Just a quick couple to look at:
SQL
Knowing SQL really well allows you to solve problems simply and elegantly in the db, rather than with unnecessary and complicated code in your application.
Icon
A very unique language. I would get the book 'The Icon Programming Language' (i forget who it's by). Icon is an interesting little language with neat things like, higher order functions, coroutines and coexpressions. And, much of it's beaury is going into Perl 6.
Actually, that was my first question for both Larry and Damian at the 2001 O'Reilly con. Was Icon an inspiration for Perl 6? And they both answered an emphatic yes.
Postscript
Everyone should know one stack based language. It make your brain more flexible.
Lex/Yacc or Parse::RecDescent
Debatedly a tool, not a language. But learning about parsing and tokenizing and compilers will help you down the line. Once again, it makes your brain more flexible.
-pete
"Pain heals. Chicks dig scars. Glory lasts forever."