IPODs have a hard drive in them, and hard drives are very sensitive to shock and vibe. Those micro drives used in the IPODs are MUCH more tolerant to shock then the variety used in a PC but they can still be damaged. Be careful not to drop it.
An autmotive (or boat) electrical system is one of the most hostile environments that you can ask electronics to work in. There is a very wide range of "normal" voltages and there are major spikes from all sorts of things. A "cheap" power adapter might not be such a deal, as they may not filter out the really damaging stuff.
Don't let the IPOD get wet, I am sure it won't like that.
If the IPOD won't respond, make sure the "HOLD" switch isn't on.