I'm currently totally infatuated with the following:

• List::Util - nothing is more beautful than functional programming
• Template Toolkit 2 - clean and readable syntax, maximum flexibility
• XML::Twig - superbly flexible, supremely simple
• HTML::TokeParser::Simple - HTML munging actually made fun
• Class::DBI - finally, SQL abstraction done right
• File::Find::Rule - very clean interface (straight File::Find can still be simpler for "non-linear" complex conditions; use a healthy mix of both)
• Imager::Graph - very pretty graphs with very little effort; antialiasing++

The following modules are basic stuff and don't get you far on their own (as opposed with the ones listed above). Still, they're so useful I could not imagine living without them anymore.

• strict - need I say more?
• LWP - feels kludgy at times, but rock solid and reliable, nevertheless
• CGI - dito
• Getopt::Long - turning q&d tenliners into flexible tools amazingly quickly
• File::Spec::Functions - symbolic manipulation makes for readability and portability
• Data::Dumper - Words cannot do this module justice. I've used it in so many different situations, from communication to debugging to logging to persistence, that it alone deserves as much praise as all other modules together. And I'm not sure that'd be doing it justice. Along with it, Safe, while not used much, deserves a mention.

Besides those, Mail::SpamAssassin and Perl::Tidy have earned an honorary mention for doing good work on my system, though I don't use them directly. I like Cache::Cache and friends, but don't need those often. Modules that might have made my "infatuated" list, had I had much opportunity to use them, include Log::Log4perl, WWW::Mechanize, DBD::SQLite, URI::Find, Inline::TT, Tie::File, Inline::File, CGI::Application, Email::Valid, and more.

Makeshifts last the longest.