I also got to drive one of the 15 passenger vans with Thomas as my co-pilot. We had the sweet setup shown below to pump our iPod music throughout the van. I love my Belkin TuneCast II FM transmitter and power adapter! There are a few cables to deal with, but once it's laid out in a good spot, there isn't a problem.

It's great for long rides because the power adapter takes care of the iPod and the transmitter, hence all of the cables. The transmitter does a great job with reception and you can choose from the whole spectrum of radio channels, so finding a free frequency is not a problem. Now I just need a new source for road trips.