What is your favorite trailer features/modifications?

We bought our trailer last summer and have been getting it setup to our liking. Wondering what other ideas are out there.

16x7 cargomate
We have ran 12v lighting for the loading ramp and the side when we pit next to the trailer. cd player with indoor and outdoor marine speakers. Fully insulated and finished ceiling All painted white and rhinolined the floor and the bottom foot of the walls. 3 rows of e-track. About 34' of tire racks. 110v lighting, and outlets on the inside and out. We added a rv step for the side entrance(super helpful!)
We have built 3 custom shelves in the front of the trailer, and the top one folds out into a bed.

We are crazy and regularly haul 5 karts. Have fit 6 before, and could fit up to 8 if we built another double stacker.