I'm brewing hard cider - what can I do with the yeast afterward?
I tried making bread once with leftover beer yeast.   It was the densest bread I've ever tasted.  Breadmaking not recommended.

You could try making vegemite.  


  How to make Vegemite.
  
  Brewer's yeast is a good source of vitamin B, but live yeast tastes
  boring, it is poorly digested. Inactivated yeast lacks the
  disadvantages, but is still bland. The inventor of vegemite solved
  this problem using autolysis: a process where the yeast's own enzymes
  break it down.
  
  Spent brewer's yeast is sieved to get rid of hop resins, and washed to
  remove bitter tastes. Then it is suspended in water at a temperature
  greater than 37 C with no nutrients: the yeast cells die, and vitamins
  and minerals leach out. Then the proteolytic (protein-splitting)
  enzymes take over, breaking the yeast proteins down into smaller
  water-soluble fragments, which also leach out. The yeast cell membrane
  is unruptured during this time, and can be removed by centrifuging.
  The clear light brown liquid is then concentrated under a vacuum to a
  thick paste (the vacuum helps preserve flavours and vitamin B1,
  thiamine). It is seasoned with salt, and a small proportion of celery
  and onion extracts to increase the palatability.


From http://www.convictcreations.com/culture/foodwine.htm (Last section on page)