Grind them up and put in flowers beds.
You can sell them as decor or ingredients for candle makers or to put in glass table tops. I once had a relatively large contract with South Eastern Anthropology stores for coffee beans they were putting into large bins and selling accessories out of.
We compost all of our spent grounds and give them to local farmers. If there is an extension office for your county, you may be able to trace some folks there who would love them. You will need to grind them in order for them to decompose correctly. It's also a good idea to buy some night crawlers from you local bait shop to help the process (you've never seen a happier worm.)
So we have a table with large bins on them in the back. We fill them up and the farmers come twice a week to pick them up and exchange the containers. Other people are welcome to scoop some out too.
The next plan is to install some drains on them so we can open the table with holes and start an oyster mushroom garden underneath. The spores grow RAPIDLY in coffee grounds.
Hope this helps.
GREAT idea!!! Keep going!!!
I just save them for new burr seasoning.