Turn Your IPod or IPhone Into a Portable Drive
Whether you use your iPod or iPhone for entertainment, communication, or to amplify your cool quotient, all models share one thing in common: They can function as portable storage devices. Depending on the model, your device features either a hard drive or flash drive that allows you to read and write files to it just like an external drive once you enable it to do so. Here's how.
Enable your iPod
You can turn any iPod (except iPod touch, see below) into a portable drive using iTunes. If you manually manage your music instead of having iTunes automatically sync songs, you don't need to do anything-your iPod is already set to function as an external drive, and will mount and be accessible on your desktop whenever you connect it.
If you set iTunes to automatically sync music to your iPod, you'll need to enable disk use; connect your iPod to your Mac, open iTunes, and select your iPod in the Source pane under Devices. Click the Summary tab (or Settings tab for iPod shuffle) and then select the "Enable disk use" checkbox. Your iPod will now mount as a drive volume on your desktop whenever you connect it.
iPod shuffle users and those with any click-wheel iPod that can be synced over USB running iTunes 8.0 or later can additionally allocate the amount of disk space that will be reserved for storage when autofilling the iPod. To do this with an iPod other than an iPod shuffle, plug in the iPod, select it in the Devices area, click the triangle next to it to expose its contents, click on the Music entry, click the Settings button that appears at the bottom of the iTunes window, and in the resulting Autofill Settings window, use the Reserve Space for Disk Use slider to determine how much of the iPod's storage media will be reserved for data. Note that this slider works only when autofilling the iPod. If you sync data either automatically or manually to the iPod, this slider's settings will be ignored.
Enable your iPhone or iPod touch
Apple doesn't allow you to enable disk use on an iPhone or iPod touch, but that doesn't mean you can't turn either into a portable storage device if it's got space to spare. Here are a few iPhone apps that'll turn your iPhone or iPod touch into a wireless (yes, wireless!) drive. You might want to look at the user reviews in iTunes first before you give them a try.
Avatron Software Air Sharing, $5 (iTunes App Store)
Magnetism Studios FileMagnet, $5 (iTunes App Store)
mAPPn Discover, free (iTunes App Store)
Veiosoft DataCase, $7 (iTunes App Store)
Aditionally, you can use Ecamm Networks' $20 PhoneView to copy files to and from an iPhone or iPod touch.
[Writer, music composer, photographer, and pack rat Kris Fong has archived tens of thousands of files. Now if she could only remember what's stored where...]