I assume you know about [link|http://developer.apple.com/documentation/Hardware/Developer_Notes/Macintosh_CPUs-G5/PowerMacG5_SP/3Input-Output/chapter_4_section_3.html|Target Disk Mode]. It lets you boot up a Mac so that it just looks like a disk to another Mac. It's good for moving things from a Powerbook to a PowerMac. There's a similar [link|http://www.lowendmac.com/macdan/01/0706hj.html|SCSI] mode too. It looks like you can't do anything similar with a PC.

Of course, an IPod is supposed to be [link|http://docs.info.apple.com/article.html?artnum=61131|great] for going from Winders -> Mac or back, but the capacity is limited. And you have to be careful about how you do music or the software won't be happy...

No first-hand experience with either TDM or iPod, just passing along some info I've picked up here and there. :-)

Cheers,
Scott.