If I do break some glass, I wrap it a bit with something to protect the guys who pick up our trash, theirs is a job with lots of risks! But by and large, I can't think of any way to use or reuse a broken piece! Think of it: back when my mother was small, they simply buried things like that somewhere, and even old cans and stuff!

I've used broken glass to make stepping stones for my garden

I used my broken glass to make a decorative garden tile!

If it isn't broken, I bring it to a thrift store or Salvation Army store

Use some broken pieces for lawn decoration