Long push prevention circuit
For some things I made, I was worried there would be a lot of trouble if the button was pressed too long. For example, if the MCU is waiting for a push, does something quick and then returns to waiting for the push, that can happen fast enough for a second push event to happen if you don't press and release fast enough. Saw it happen with the LCD's and I wasn't going to risk that happening all the time at the presentation - having to clear the screen and retype things a lot of times isn't exactly impressive. So I made this (which I recently saw can be done with 2 transistors a lot simpler - though I don't have a very good relationship with transistors anyway...) which prevents a button from giving a signal for more than a fraction of a second even if you keep pushing the button. It has the side-effect of making really quick successive pushes last less, depending on how fast you push, but I didn't make this on the breadboard so I don't really know if it matters much.
Import data for Circuit Simulator
Again, not the sexiest one, but I prefer my designs to work first and be pretty last ;)