I always thought I would do it. I agree with you - I am not using them - would be nice to help someone else out.
But what worries me is the legal implications.
As I would not feel that the child was in any way mine it disturbs me that they would be able to know that I was their egg donor. then perhaps turn up on my door one day saying 'mummy??" (bit dramatic - but you know my point).
(this is the case in NSW - it might not be the case in other states: http://www0.health.nsw.gov.au/art/egg_embryo_donor_after.asp
I completly understand the child's right to access their genetic information. but I would not see that child as my child so....
Because of this moral conflict I would not donate my eggs. the situation is just too complicated - but the answer for me is simple. it is a shame that this means that someone misses out on donated eggs.