What kind of business would make a cool and original tycoon game?

There are a lot of tycoon games out there, and it seams like they let you do almost anything, from running a small bakery shop all the way up to running a giant transportation empire.

I my self am working on a little tycoon game of my own, one where you run a stamp collector/dealer shop. While working on the game, I have started to realize how I could adapt the core of the game to make other tycoon games, so I decided to ask this.

What other real life businesses would make a good and original theme for a tycoon game? It could be more or less anything, such as a mechanic’s repairs shop or a dentists surgery. It does not even have to be a business, a government organization such as NASA could also work.