I have had the idea of making a "circular" mount that worked from 1-4 fans. Best way I can explain is with 1 fan: looked traditional, 2 fans: one above one below, 3 fans: you would see two thirds of each fan layered over each other and 4 fans: would see a 1/4 of each fan. And this keeps them tight to the wall.
Here's how 3 would lay out, think of a circular shingled pattern...
(of course some "maker" will see this and make millions off it, but if you like it I'm willing to share)
MK M GOBL
Yup I'm a FANaddict!