The fine folks at macresearch.org have put out an interesting tutorial that walks through setting up launchd and rsync to do automatic backups whenever a specific external drive is mounted. Loyal readers may note that this is similar to the core feature of Martian Lifeboat (which should not be confused with Mojave Shade's Lifeboat, as mentioned in several comments). The script, however, is free; Martian Lifeboat is not.
Although the currently published script leaves out the crucial -E flag to force rsync to copy resource forks (credit to Josh Wisenbaker of afp548.com for spotting the silent E), it's still a good primer on the power of launchd. For a simple way to create your own launchd configuration files, be sure to check out the powerful, open-source and free Lingon utility. If you try this out, let us know how it works for you.
[via macenterprise mailing list]