Typescript with modules

Is anyone using the typescript watcher in a way that combines more that one .ts file in a tsc command? What I'd like to do is set up a rule that bascially builds one .js module from all of the .ts in a given folder, whenever any one of them changes. I think it's not too hard to do, but I thought I'd check and see if anyone else is doing it.

cheers,
~Bill