Here are my favorites:

• DBI - I do a lot of database work, and a lot of times I just need to see if a DB has a table or is available, so I use 'dbish' a lot. It's also a quick way to figure out what DSN's are available on your machine.
• CGI - cgi scripting. :-)
• CGI::Application - more often than not, defining callbacks for actions is a lot easier than straight scripting.
• HTML::Template - use this with CGI::Application for faster web app prototyping.
• DBIx::Recordset - has a nice interface.
• HTML::TreeBuilder - once you wrap your brain around this one, you can scrape data from any web page you want. There's also a module HTML::Seamstress which uses this to create a better HTML template system than HTML::Template (IMHO).
• Tk - sometimes it's nice to have your favorite script with a GUI interface. :-)

Update: Here's another one:

• CGI::Session there's a cookbook and some good tutorials for using this module.

I use several others but these seem to be the most used in my arsenal, and I am a frequent surfer of CPAN, always watching out for anything that makes my job easier.

Cheers!

--
hiseldl
What time is it? It's Camel Time!