Turn your iPhone into a hard drive for $10 with iPhoneDrive
This piece of software will let you save and store files on your iPhone.
One of the features iPhone users don't get to enjoy compared to their iPod brethren is mass storage--the option to use the device as a portable hard drive. Despite the iPhone's 4 and 8GB capacities, Apple isn't giving folks access to that beautiful free space. Not to fear though, eCamm Network has iPhone users covered with a $10 piece of Mac software called iPhoneDrive that turns the phone into a mass storage device.
Once installed, the program lets you send files of any size (iPhone storage permitting) back and forth. It also supports drag and drop. Unlike similar products for the PC, like Mediafour's MacDrive, the iPhone won't just show up as a storage-ready device in your finder. Another thing to note is that this software requires the latest version of Mac OS X, and iTunes 7.3, so Panther holdouts are out of luck.