Email as command line
Just read E-mail as a System Console. Part I over at Linux Journal. It's something I've been meaning to implement for awhile, using CPAN:Mail::Audit and other tools. Got a bit of a start on things, with a sort of plugin system for adding commands available via email. Maybe I should hit this again.
Personally, it's been a long, long while since I had a dialup-based system - so I don't have to solve their exact problem. But, it would be nice to fire off an email to myself or some other mailbox I own, formulated just so and cryptographically signed by me that would cause some machine behind a firewall to open up an SSH tunnel to a predetermined location somewhere. Among other things.