Glass can be recycled and used for a pottery glaze! And unlike other reuses of glass, using it for a glaze doesn't require any special equipment beyond what one would use for any other glaze making or pottery. You break the glass, crush it fine with a sledgehammer in a bucket or similar, screen it, and measure it out (50-60%) for use in the glaze recipe. For obvious reasons, colored glass is more interesting, and different colors of glass are used in different glazes. Oh, this is very exciting. :-)

Note: not a project to be executed around kids.