You know that "Enable disk use" checkbox? The one that appears in iTunes for most modern iPods? That checkbox isn't there for the iPod touch. The touch provides no built-in disk access utilities but if you have an Intel Mac, and aren't afraid of the command line, you can use these Media Folder utilities to copy files to and from your touch.
The utilities, which are based around a modified version of iPhuc, work with the iPhone as well as the touch and copy files to and from the Media/Documents folder.
Update: PPC Mac users download this copy of iPhuc, rename it to util and stick it into the media utilities folder. It doesn't run as cleanly as the version I converted--lots more extraneous text--but it works on PPC.
