I have started keeping a notebook about the quilts I do. This is because, sometimes, I will find that the block I used worked great, or it didn't and I list changes that I do. I also put a picture of the quilt in there, and who it was given to, and the reason for giving it.
I also write down things I would like to do differently next time, and things I learn along the way.
I figure it will help me, but also my children may learn something from it.