Curious what folks like to do with spent coffee grounds / espresso pucks / stale beans. Personally have tried to use as fertilizer with limited success, used as a substrate for growing oyster mushrooms, and in cooking (brown bread made with some stale espresso grind really helps the flavor).
I have made a coffee vodka. Saved the grounds up for days, only to realise you don’t need much to make it! Left it for much longer than the recipe said, but that was because I wanted a stronger coffee taste.