Zoo Tycoon: Dinosaur Digs

Unlimited Money:
Just press the $-button ! Press it again for more money ! Be prepared to repair fences. This cheat causes fences to crumble and animals may escape!

or

Press $ and shift and hold them and watch your money go up rapidly! Make sure you do it at the beggining of the game when you have no enclosures otherwise the fences will break and your animals will escape.