I keep a quilt scrapbook. I started it about 10 years ago, when I realized I had forgotten about a whole lot of quilts I made for friends when we were all young mothers. I made the first section to be about family quilts - ones that my G'mas and sis and brother made, then started adding mine - took pics of the old ones that were still around, and then added my ne ones as I completed them. I do it sort of scrapbook style - pics of quilt, closeups if applicable, with recipients, journal notes about source of pattern, completed size and date, notes about the process, fabric swatches, disposition of finished quilt.
I often forget what I have done, and the scrapbook gives me a little more memory than my brain!!