Funtionality updates/upgrades

Something a bit different- has anyone else done "upgrades" that can significantly improve the driving/safety/comfort experience? I'm not talkkng lift kits, or wheel/tire combos, etc that can be a matter of personal preference (although I suppose some would question my personal preferences for these upgrades no doubt)
BTW 2009 Outback 2.5 (I suspect its a SE, has leather seats with a M/T)
1 Added a Android head unit. I think this has been my #1 upgrade. Modded and placed the center cubble hole in the radio position, and trimmed center heater vents so it would fit a 7" android unit.Made a bezel to slip between the console and the head unit .
Gives me a lot of functions for what I consider a bargain price, with a fair amount of further customizing (See below)
2 . OBD-II reader - Added a bluetooth reader to the OBD-II. When paired with the head unit and using a app called Torque Pro, can read all the performance parameters, and reset codes "on the fly" (Nothing like starting out on a 400 mile trip and have a PO420 light up 10 miles down the road)
3 Powered USB ports Head unit had 2 usb ports available (1 data/power, 1 power) After doing the headunit /cubbyhole swap, had a approx 3/8-1/2 gap at the lower edge. So I added a USB hub w/12 volt input , wired into the accesorys fuse, and connected to the head unit. Keeps the phone charged and makes internet connection much easier. Plus, gives me 3 other port to plug in usb sticks and other gizmos. Havent tried a USB Hard drive (yet)
Add ons to come- may or may not happen
Rear view camera. Will happen, just ran out of time before Winter hit. Probably will do at same time I work over the rear hatch wiring
Seat heaters for the rear seats. On the fence with this, but think it could be done fairly quickly and easily- Bottoms anyway.
Heater vent for the rear seats. Grandsons complain about not getting much heat in the back, so I've wondered about designing and 3d printing some small ducts that would direct some of the heat from the front to the rear. Most of the time I'm roasting up front with everything on max, so diverting some not a bad thing IMO.
Thoughts/Ideas?