I know a crank bait rod has its main use but what else can a mh/m 3/8- 1-1/2 lure weight be used for if anything? Its a 7' foot crankin stick.

Mod describes where the Rod bends not necessarily how easy it bends. I don't usually like slower actions for spinner baits but if the hook is sharp that rod might be stout enough to get a hookset. Same for swim jigs. If you do any cat fishing that's a possibility too. 

It's Perfect for Chatterbaits and Crankbaits ? 

You can use it for all treble hook baits like topwater, jerkbaits & cranks. It could work well for frogs, blade baits/chatter baits & jigs if you are using braid. 

Anything with treble hooks if the bait weighs enough to load the rod. My preference for single hooks is always fast or extra fast action.