I've got what I consider to be a poor memory. Or, at least, I try not to rely on it too much (perhaps that's why it's no good?). But anyway, I have a hard time remembering what the current speed limit is when driving. On my drive home yesterday from my holiday travels I got an idea for a helper. I was thinking, if you make a felt cover for the top half of your steering wheel (say), and indicated on it mileages from 25-65 in increments of 5, then with another felt ring you slide around to the appropriate place, you'd have a handy way to remember the speed limit. As long as you remember to update the position of the ring when you see a new speed limit sign, of course. I suggest felt, because it seems to me that two layers of felt might hold eachother together mostly, while still allowing some freedom of motion.
I dunno, maybe it's a poor idea. But as of right now, I like it. Plus when I tell my mom about it, it'll give her something fun to do (she sews, rather a lot).
Of course, it's only a temporary solution until the speed limit signs communicate wirelessly with a sensor in our cars that changes a heads-up display on the dashboard which always indicates the current speed limit. Unless, of course, self-driving cars come around before that, and the issue becomes moot.