Sometimes you need a handy mobile storage device to move files around between locations. You could use a flash drive or an external disk, but why not make use of that 16GB phone that you carry with you all the time?
iPhoneDisk is a MacFUSE based filesystem for the iPhone. Simply install MacFUSE, then install iPhoneDisk, and your iPhone will be usable as a general storage device. When you connect it via USB, it will show up on your desktop just like a USB drive would. You’ll always have a convenient external disk on hand, and it’s one less thing you need to carry around with you.