Stunts Scenery Generator
Also known as SSG, this is a scenery creation utility created by Wayne Buttles.
This program creates a random scenery (with boats, tennis courts, trees, ...) for any existing track files. Most of the frequencies can be controlled by the user, for example to get more buildings.
SSG is command-line based DOS program, so it is hard to use for people who doesn't know DOS and is not user-friendly at all. But it is an easy solution to add scenery on one of your track if you have no idea for your scenery.