If you want to take this further, it’s not expensive to have a printer create custom cards for you. Make a layout in anything - Illustrator if you can, or a text editor if you want. You can either give the printer an Illustrator file, or you can just give him a laser-printed version of a text file, that they’ll shoot to reproduce.

Check out the card stock available, the colors, and get a few thousand cards. Try making different layouts for different things: action items, someday maybes, etc. Different colors for different priorities; you can do whatever you want.

It’ll cost a bit more than stock cards, but think of the ease of use of having cards with your own headers, lines, checkboxes - whatever!