In a grade 7 inventor fair I painted a toilet seat fluorescent green and called it a glow in the dark toilet seat. I won 1st prize, why didn't I follow through with it? That's a wicked idea.
Just the other day I had to use a bathroom without a window while the power was out. I was lucky that I have a good aim and knew the place like the back of my hand, else something would've been sprayed. That toilet seat would've been a godsend -- I think you have a market.