Here's a bad idea: a desk that attaches to the bottom of your steering wheel. Not only does it promote doing work behind the wheel, which is an obvious distraction, but it appears to also make it impossible to really turn the wheel.
Sure, in theory this is meant for use while parked. But guess what? People will use it while driving, because people are idiots. And do you really want to be on the road with someone doing their taxes on a desk attached to their steering wheel?