I can’t remember what I used, but I managed to wipe everything in my iTunes library once, about 74Gb, found an app that copied everything back from the Pod. The first one I tried would only allow a small number of tracks at a time, so I had a hunt on Google and found one that cost around $20, and did the job beautifully.
Got family around at the mo’, if I get a chance I’ll have a look later, see what I used.
There are quite a few around, you shouldn’t have any issues at all, in fact I think of my iPod as a back-up for iTunes, although it’s getting close to full up, now, at 155Gb. I’m really hoping Apple bring out a 256Gb Touch… 😉