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.
• Interfacing between C++, JavaScript, and Flash code
• 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.