File Storage for iPhone & iPod Touch

"DiskAid is a tool for Mac and Windows which enables you
to use your iPhone or iPod Touch as an external Disk.
With DiskAid you can transfer files and folders between your
iPhone or iPod Touch and your Mac & Windows Computer."

No Jailbreak needed. And it's FREE!

Macworld article about DiskAid by Dan Frakes

DiskAid website & FREE download