50 icons total with lots of subjects. Please feel free to take/use whatever strikes your fancy. Credit to craterdweller. I think there was only the one 25 square graphics card, but if anyone needs the original card image I can link it. I've labeled the icons by fill so hopefully it makes sense.
Feedback/comments always welcome. If you have a question on any of them (ie subject, why it fits the square - etc) don't be afraid to ask :)