Anybody who plays Runescape will recognize this. They have a pin you can set to gain access to your in game bank. It has a fair few security features to combat keyloggers which were (and still can be) a major issue.

Some security features I can recall.

Random layout of the numbers on both the button itself and which button has which number. This is shuffled on every click.

Upon clicking all numbers and the mouse pointer vanish. This prevents screenshots taken on clicks by some keyloggers from working.

No keyboard input. Annoying but needed to combat keyloggers.

http://vignette2.wikia.nocookie.net/2007scape/images/c/c3/Ba...

My bank did that with a JavaScript number pad. They went back to a standard password field with the new design of the site a couple of years ago. That made me feel less safe because I understood why the were complicating the input.

Another strategy I've seen is to ask some random digits of a longer PIN, with a mask to fill out.

I've seen some secure financial sites that already do that.

Convenient option on Cyanogenmod. Been using it for about 2 years and it's surprisingly easy to get used-to.