Saves me more headaches than all others put together!

Next I am a fan of Exporter. Allows me to write my own procedural modules and export the API in a way where I can afterwards move stuff around. (Even if I don't, just knowing I have that freedom is nice.)

As for doing tasks for me, probably DBI. Then LWP. I also have liked DB_File for a while for no particularly good reason. Oh yeah, Data::Dumper is handy... :-)