If you go to Ridge Road Station, under their links they list clubs. They have a few web pages, none in Indiana. However, they do list snail mail addresses and there are 4 for Indiana.
I know of three active clubs in Indiana. In no particular order:
Indiana Big Train Operators (or something like that). Out of Indianapolis. Occasionally meet at Watt's so you could ask for contact information there.
The Fort Wayne group. I think you could ask at Phil's Hobby Shop in Fort Wayne about them.
The previous 2 occasionally get together with the club in Cincinnati to view each others railroads.
The Illiana Garden Railway/Railroad Society centered in Valparaiso which Al mentioned. One member lives fairly close to you.
Hope this helps