Have you ever had any ideas that if you had pursued them might have made you rich? I've had a few, but realistically there is no way I can break into those particular markets.
For example here in the Uk we have vehichle number/licence plate recognition on some car parks as you enter them. A message board will then tell you how long you can stay for free.
Now maybe this has been done somewhere already, but why not take that a step further. For example why not get rid of the print out tickets to display in the window. When you come back to your car you enter your plate number in to the automated payment machine and it tells you how long you stayed and the total cost, which you then pay. Using this approach it could be charged on an incremental minute system, so you pay for precisely the number of hours and minutes you stayed. Until you pay the exit barrier will not open when it recognises your plate on the way out.
Another idea I had was why don't car manufacturers build an extra strorage space into the chasis of cars, particurlarly in the boot/trunk, in much the same way as you have one for the spare tyre.
Over this storage space they could put a thick metal plate hinged at one end with heavy duty hinges. At the other end could be a padlock hasp, which you could pop your own heavy duty padlock through. The overall idea is that you would have a built in safe to store laptops, cameras, etc instead of a easy to break in to glove box.