If you haven't already, learn DBI. It's kind of a cliche, but create a catalogue system for your DVDs. Set up MySQL, install the modules you'll need to interact with it, design the structure of your tables and write code to read from and write to your database. Once this is working, you can write a web front end for the system in PHP (although I'd go with mod_perl ;).
Not at all... Write a command line ( or curses) perl interface first. As I mentioned, you could also do a mod_perl web interface instead of php. You could do a tk interface once you get more comfortable too...