I've also spent tonight thinking about the toy trains, as I've not really done much in the way of concepts/designs for them. All we agreed on is that they will be simpler versions of the real train and maybe with some nice wood shaders. Aaron has found some good shaders and I've been continually hunting for more and looking at tutorials on creating custom shader networks. Thank you Lee Lanier for 'Advanced Maya Texturing and Lighting'!
Here's the rust texture shader network I used.
It's just noise.