I'd go with:

• DBI for pretty much everything
• CGI::Session - recently began using this extensively after being forced to use php for a year.
• MIME::Lite use this a lot. Best interface for sending mail IMHO.
• Data::Dumper - I use this ALL the time while developing
• WWW::Mechanize
• HTML::Parser - I love subclassing this module to create "MyParsers::SiteName::Page" interfaces to use with WWW::Mechanize.