Are you still carrying around a USB thumb drive as well as your iPhone?  Well DiskAid from DigiDNA is a free application for both Windows and Mac that allows you to use you iPhone or iPod Touch for file storage! Best of all it does not require you to jail-break your device.  Check it out...

•     DiskAid is a Freeware, 100% free of charge
•     PC Windows & Mac OSX compatibility
•     Auto detection feature, just plugin it in !
•     Copy Files & Folders between your iPhone or iPod Touch and your Computer
•     Files & Folders Browser
•     Drag & Drop
•     Features rich file organization including folder creation, renaming... etc.
•     No jailbreak needed
•     Supported firmware versions : 1.1.1 to 1.1.4

www.digidna.net/diskaid