It seems that if we had a lunar base going then we would be more likely to invent things that would improve space travel. It also seems that private industry is faster at developing these improvements than if we leave it to governments alone. So is there any commercially exploitable resources we know about on the moon that could be commercially viable as an industry?
The moon's gravity well is deeper than most asteroids. Therefore, materials that can be found on both asteroids and the moon are probably not going to be cost competitive when sourced from the moon. However, there are some materials that might be on the moon that aren't on asteroids. Water and Helium isotopes come to mind. Also, the moon has a unique resource that other bodies don't: its relative position to the Earth. In particular, the far side of the moon is a very quiet place electromagnetically speaking.
By far the most abundant resource on the moon is Oxygen. It comprises a little less than 50% of all the material on the surface of the Moon, and some of it can be extracted reasonably easily. If large production facilities were built using local resources to produce Oxygen, the Oxygen could be used as 89% (by weight) of the fuel needed by rockets in orbit. Hydrogen, the other 11%, could easily be brought up from Earth in large volumes.