If you can bring a laptop you dun need to buy anything at all.. (or if you can find computers to charge your ipod on the trip). If not, you can buy iPod USB power adapter. Here are some of the power adapters you can find on apple website:
http://store.apple.com/1-800-MY-APPL...r&mco=C39415D1
Or you can go to local store and ask for a power adapter for iPod... I believe there're other brands making such thing. Personally I will buy apple made products tho... just the sense of safeness