The next time I see a person smiling to themselves ( you know, they've got earbuds, either on a call or having a funny thought ) I'm gonna walk right up to them and say: " Thalia? Is that you? " . Because you have to be smiling when you come up with these muses :)

As for the next nomenclature, great ideas above. I hope it's a happy term. Or make it a symbol ( like Prince ). A good ‘ol yellow happy face.