The Test:: modules are absolute essentials for me. Never develop without them. Once you get test infected you won't either :-)

Although Test::More has been core since v5.007003 other useful things like Test::Differences, Test::Exception, etc. are not.

Other essentials for me include:

• Template - I like templates. Template Toolkit meets my requirements best.
• AppConfig - saves me typing and makes all my apps work the same.
• CGI::Application - saves me code and encourages me to be good
• DBI - the best DB layer I've come across in any language
• CPANPLUS - makes automating CPAN installs so much simpler
• Class::DBI - saves me so much typing when developing DB applications
• Exception::Class - I like exceptions
• HTML::Parser - is my friend for messing with HTML

Updates:

• 20020922 - made "test infected" a link - thanks ignatz