Here is a link to a form that the Lost Quilt Come Home website suggests.
http://lostquilt.com/qd.pdf
It is very thorough documentation, including places for photos and fabric samples.
They say to feel free to make copies of it and distribute it freely.
I have just started documenting my quilts because I wanted a way to track show quilts and then decided I'd also like to track the quilts that I make to give to family and friends as well. I did a streamlined version of the Quiltmaker's documentation. Just the information that I couldn't get by looking at the quilt (like batting used, current location of quilt, appraised yes or no, etc.). I did one page for each quilt that is still in my possession. Quilts that have been gifted did not get a page as I don't have enough info on the ones that I remembered to do much more than list them and who they were given to.
Rob