I know this may come as a startling revelation, but Xander likes trains! Specifically Thomas the Tank Engine.
Things I have bought in the last few months with Thomas' image*:
and, in a moment of insanity, underwear
I will also most likely be buying a Thomas bathing suit, when I come across one.
Train related things I have bought;
diaper covers (okay, that was more for me than him)
And then there's the huge set of trains and tracks we have on long term loan from Kristin.
*this doesn't even count all the Thomas stuff he got at Christmas, per my suggestion