title_body: Use for old grounds?
upvoted_answer: They are very good as de-odourizers, we use them in the kitchen and sometimes in a small perforated plastic container in the footwell of the backseats in our car.
  
  The fragrant smell lasts a long time also surprisingly.
  
  Also it seems to be useful in fridges too.
  
  That link lists the following:
  
  
  Deodourize fridge
  As a scouring agent
  A cheap varnisher
  Dye for paper
  Promoting Hydrangea health
  Ash absorber
  Exfoliant
  Cockroach trap
  Fortifying plants
  Compost
  
  
  So the above is quite a good list of uses that could be applicable for your situation
  
  I just found 34 uses here too, I have to say though that using ground coffee as a method for salting a path didn't work for me.
  
  Additonal uses:
  
  
  slug killer
  mushroom grower
  carrot and radish feed
  worm attractor
  cat deterrant (this didn't work for me)
  play doh dirt
  make a pin cushion
  garbage disposal cleaner
  drain cleaner
  add weathering to wood
  meat tenderizer
  make energy bites
  egg dyeing
  coffee candle
  make fossils
  treasure stones
  paint
  flea bath
  remove build up from hair
  eye bag remover
  deodorizing salt
  salt scrub
  face mask
  path/road ice melter