Parse::RecDescent - I am an old lex/yacc language designer. The other day I actually had cause to write a little language. I am overwhelmed by how flexible and powerful this module is. All the joy of yacc without all the pain of yacc Thanks Damian!
Quantum::Superpositions - Takes a whole class of simple operations that were too complex in Perl and makes them simple again (comparing lists, set operations, etc).
DBD::ChartDBIx::Chart - there is nothing like charts to make PHBs happy. And there is nothing like a package with which you can implement them in minutes to make you look good.
Data::Locations - makes it simple to build text when you don't necessarily want to build it sequentially, like when building a web page. You can define handles that print into a specific part of your final output. So you could define a skeleton of a web page, have a script handle, a style handle, a body handle, etc. Write the appropriate stuff to the appropriate handle then dump it at the end.
Date::Calc - All the date manipulation I ever need, in one place.
Spreadsheet::ParseExcelSpreadsheet::WriteExcel Allows you to use excel as a data entry mechanism. A great alternative to web forms for really complex data, or for management-type users who a very proficient in excel, but not-so-good elsewhere, Also a great report generation method.
CPAN - best mechanism ever for automated installation. It's the life blood of what make Perl sucessful. (Although I hear the CPANPLUS is even better. It's on my short list of things to try).
Snippets of code should be wrapped in
<code> tags not<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor