Heres a couple things I have done recently:

Rhino lined whole interior floor

removed the head liner and painted the roof gloss black

fabricated a mount for my fire extinguisher with quick release clips

removed the fabric from the back of the seat and installed heavy rubber vinyl matting

mounted my amp to the back ot the rear seat so it fits below the spare tire

 

Oh ya

built myself a switch box and painted my interior gloss black