I was thinking about this few days ago. I just can say I can't use any other technology after meeting Perl. As neniro said, there are nice things in Python, Ruby, Java and PHP, but my opinion is Perl can do everything they can, but those can't do what Perl does.

So, my suggestion is: learn other usage for Perl than sysadmin scripts :-) There are a plenty of nice modules in CPAN that does about everything: from resolving card games to complex web applications, workflow control, etc. Improve your knowledge doing that, you'll see Perl always will surprises you ;-).

Update: After reading mrborisguy reply, I must emphasize that I am a former Java and PHP developer with unix background. The above text applies to me. I tried to perform the same tasks I do with Perl in Ruby, Python and Java but it really disappointed me. I think the only aditional language I would invest my time with is Ruby (after trying Ruby On Rails, but I switched back to Perl after I discovered CGI::Application and Class::DBI ;-)