I think organ donation would be a good idea, but not every part of me. Only the best for the living!
I don't count myself amongst the "irreligious", its too broad a brush as there are religions congruent with an atheist position. In addition to a non belief in deities explicit in atheism, I'm also a monist in regards to the mind/body question.
So; here's my take from that perspective:
 - A Frisbee is a real-world demonstration of; the Bemoulli Principle, Newton's Third Law, orientational stability via angular momentum and aerodynamics, so …Science!
I wonder if you can 'will your body' to any institution any where in the US?. There are also the 'body farms' where your remains can be put for further research.
'Body willing' seems to be gaining popularity simply because of funeral costs: http://www.kens5.com/news/Funeral-or-donate-body-to-science-UTHSC-s...
Yes, no qualms whatsoever.
They are welcome to it if they can use 63 year old body parts..
They can have the organs...dunno about the rest...
I'm a organ donor, although I doubt my used parts would be of much use (to many burnt offerings in this particular temple). I have also donated my body to science and don't really care what it's used for. My body is just the housing for my persona - when the persona is gone the rest is just trash.
Yup, already got it set up.