One of the leaders in Macintosh diagnostic tools has come up with a clever use for old iPods: turning them into mobile help centers. Load TechTool Protogo ($135) onto your Mac and you can then use the software to install customized start-up and repair tools on unused portables. This handy app allows you to create devices that will boot OS 9, OS X, PowerPC, and Intel chip Macs, or even create an exact duplicate of your system, if you have enough room.
Use the Protogo installer to choose which profile to install on your portable device.
Unfortunately, PowerPC Macs will only boot from FireWire devices, so you'll need a really old iPod for pre-Intel systems. On the plus side, the software will load on any external storage device, not just iPods. You can even create an eDrive partition on an external hard drive to use for booting and repairs.
Once the app is installed, you boot up from your portable and select which TechTool diagnostic tests to run.
When you've created your portable repair kit, connect it to your Mac and select the option to restart. Your machine will then boot from the portable so that you can run TechTool's excellent system tests. It found and repaired some small Finder issues quickly in our testing. The manual is too sparse, going into detail about the Protogo installer but not including information on the TechTool tests themselves.
A free tech support number (M-F, 12-8 EST) is listed prominently on the manual and our calls were answered quickly and knowledgeably. New users are supposed to get 30 days of support, but we weren't asked registration information when we called.