I'll try to stick to the more unusual things, since most of what I do with Perl is pretty vanilla.
- Processing camera input
- Generating graphical OpenGL output (OpenGL::Simple, attempting to use OpenGL, a few others)
- Processing SDL events (keyboard, mouse)
- Sending and receiving automated Jabber messages (Net::Chat::Daemon) to monitor autobuild system, wiki edits, manual builds, etc.
- Monitoring revision control systems and running checks, sending out commit messages, figuring out who to blame for the commit(s) that broke the automated build, etc.
- Implementing Perl-style "regular" expressions with backends in Perl5, Parrot, and C.