Did you know some breeds of chickens can be feather sexed with good accuracy?
They say feather sexing can be done between 1-3 days old. I prefer feather sexing between 3-5 days old (day 4-5, for me, being ideal on the tinier chicks from small pullet eggs and day 2-3 for regular size chicks). I have only feather sexed layers of some breeds but have done so with pretty good accuracy.
I’ve compiled a few websites on feather sexing:
http://animalsciences.missouri.edu/reprod/ReproTech/Feathersex/
http://scratchcradle.wordpress.com/2012/04/19/chick-sexing-techniques/
http://www.daff.qld.gov.au/animal-industries/poultry/care-and-husbandry/chicken-sexing
http://www.daff.qld.gov.au/animal-industries/poultry/care-and-husbandry/chicken-sexing
And once you’ve read through those, try your hand! http://www2.ca.uky.edu/smallflocks/Feather_sexing_practice.html