I once thought I would do a blanket in these tiny granny squares but got tired of it long before the blanket was finished. So what to do with all the little squares that I had already done? One thing I have used them for are these refrigerator magnets. They are easy to make but you need a very strong glue to prevent the magnet from coming off when you move it around.
The little squares are glued on to pieces of quite hard plastic that I cut out from binders/files that you use to store papers. The plastic for the picture frame is cut out in one piece. The magnet/-s is glued on to the back side of the plastic piece.
To make the squares small enough with my regular 8/4 crochet yarn, I have made them using half double crochet instead of double crochet (american terms) and only two hdc together and two chains in the corners instead of three. Like this: