A lot of forging projects are restricted by the size of you forge chamber and the port ( opening) for the metal. Fredrick's crosses are great projects and good sellers, but require a larger port or a side/end door.
Assuming your forge has the room:
Forged horseshoe sculptures and projects are great fun and good sellers. All you need is a box of old pony shoes, a wire welder, and a lot of imagination.
Tomahawks are fun to forge from old ball peen hammers, rasps, etc.
Old files and rasps can be forged into "snakes", and other critters.
Square mild steel stock can be made into fireplace tools with dragon's head and other shapes of handles.
Insects are fun to make from nails/bolts/scraps and "found" things.
Coat hooks, bottle openers, plant hangers, shop door/drawer handles that look like knives, ..............