There have been issues over the years about the edibility of avocado seeds/pits/stones, which has also included whether leaves from Guatemalan type varieties might pose health issues for some animals.

http://www.ucanr.org/blogs/blogcore/postdetail.cfm?postnum=27464

So what can be done with them that arent controversial?  They can be composted to make a rich plant amendment. Avocado pits and skins are fairly high in protein and they make a great addition to compost piles.  When added to a pile, they should be chipped and they need to be thoroughly mixed and aerated with higher carbon materials or they will start smelling pretty badly. Like really badly.  But it's great stuff when it's done.

It seems there is now another use for avocado pits - forks and spoons!!!

MADE FROM RECLAIMED MATERIALS - Transitions2earth® AVOPLAST Cutlery is made using 70% avocado seeds that are reclaimed from processing of avocados. Every year 300,000 tons of avocado seeds are discarded after the processing of avocados. The making of AVOPLAST reclaims some of these and upcycles them into functional bioplastic.

Another way to consume avocados.