The best iPod Touch/iPhone app, I think, is DropBox
*. Free 2GB of cloud storage that is probably the least complicated and most manageable cloud storage available. Drag your files into the folder. That's it. You can access them on your iPod whenever you have internet access. The folders are also extremely useful in syncing files between computers. It's really great for syncing music too, and while the free 2GB(2.25 after a few quick tutorial steps) isn't that much, it's enough to store a somewhat-appreciable playlist, and there are simply a lot of clever ways to use it with or without an app on your portable device.
*Note, the link is totally a referral link for the service. I get extra space for sign-ups through this link. If you are completely against the idea of giving me credit for a referral, feel free to go to the regular domain yourself.