General tools:

• Editor: vim, with a rather simple set of rc files
• VCS: the one and only darcs
• Shell: bash with a nice meaningful prompt
• Perl: I tend to avoid perl for "shell script replacements". If i'm using it, it better be done right, or in a week i'm too scared to maintain what I did.

Perl tools:

• Data::Dumper - with $Data::Dumper::Maxdepth usually set to 2 or 3
• Devel::Cover - I use it not only for testing coverage, but also for analyzing code paths, to simplify control flow
• Devel::Sub::Which
• Devel::FIXME
• Test::Harness's prove
• Class::DBI + SQL::Translator + a not-yet-ready home grown project = DB agnostic persistence
• Event - I use it instead of select nowadays
• IPC::Run - for it's robustness
• Tie::RefHash and Tie::RefHash::Weak - for cross indexing objects.
• Data::Structure::Util - for handling weak refs when Tie::RefHash::Weak starts nesting.
• Set::Object - when I only need to know if an object is relevant.
• Class::Delegation - for cleanliness
• fields - butchered for 5.9 goodness... Multiple inheritence support.
• Test::MockObject or Sub::Override for faking edge cases and simplifying test setup
• Test::Deep