Clothing in a stuff sack is okay if you have extra clothes, except that the stuff sacks I use are slick and won't stay under my head. My down jacket would make a decent pillow if I had a different stuck sack, but I don't take it on the majority of trips, and it's too heavy just for a pillow.

I used to use a Thermarest pillow, which was 8.5 ounces in the small size with "overfill" (added from another pillow). It uses those bits of foam that have been cut from the mats. I decided to make my own in a similar style, using a Cocoon coolmax pillow case and pieces of foam cut from a cheap mattress topper. The case is 0.9 ounces with the drawstring and flaps cut off, and I used 2.6 ounces of foam. I may add a little more foam, but it's just as comfortable as the Thermarest for me.