I used Perl quite a lot, because at the time that was the simplest thing to read a text file and use regular expressions. I wrote a Perl cgi-bin script that would let you surf the web in Elvish letters, and I can't believe that it's been 16 years since The Fellowship of the Ring.
I've learnt Python since, and I would probably use that instead now. It's more verbose than Perl, but the additional readability more than makes up for it.