I take photos of finished projects, who got them, for what reason, the pattern I used, fabric line (if possible), size of the quilt, total yardage used, and the COST of fabric (current retail price - NOTSALE PRICE), thread, batting, long-arm quilting fee (if relevant). I have had to re-create only a few quilts which were stolen from the owner during a move, and this information came in handy for the insurance company's replacement cost payment.
If I a technique or fabric/pattern combination is giving me heartburn, I will photograph the steps to get me out of the construction mess. I had to do this with a quilt of leftover 2.5" flannel squares - the bulkiness was giving me fits at the seamlines.
If I think I'd be willing to teach ths pattern or technique, I take pictures of the steps as well to include in my directions for the class.