Another theme that always interested me was model trains. I had a large H0 sized collection when I was a child, but never had LEGO trains. Two weeks ago I decided to give it a try. Trains needed more investigating than Technic because there are multiple generations. I wanted to have a fully programmable solution which could be also run longer period of time on exhibitions. The latest generation with power functions and IR remote is not really good for this purpose.
I decided for the old 9V system which was discontinued by the end of 2007. I quickly built up a collection from eBay. Model trains are very popular in Germany. Next step will be to use non-LEGO DCC digital controlling.