Thanks to Zec:
Each version of Trainz (Well, TRS04, TRS06, and TC1/2 anyway, not sure about earlier versions) had these sorts of things:
TRS04 has (that I know of):
alt + MMMG - randomly places trees, textures and hills/pits on the empty map
alt + fly - allows you to 'fly' around the map, and view from practically any angle
alt + walk - allows you to move around at 'head' height around the map
alt + smite - removes the menus, and allows you to 'destroy' objects/areas of the map. Click on an object, and a lighting bolt shoots down. The object is then deleted and a burnt looking texture is placed where the object was.
alt + lucyinthesky - makes the sky go psychadelic
alt + carz - then mouse click on a car on the road and you'll get to ride in it.