Inflatable down pillow

Exped inflatable pillow slipped into the pocket of Goosefeet down pillow.

I'd be thrilled if any one of the UL sleeping pad manufacturers would incorporate a built in pillow right into the design of the air mattress. Overall it would add less weight, I think, than a separate pillow. It looks like a couple (REI, NEMO) sort of add a bit of a bump at the top of the pad, but that's about all I see. Perhaps pillows are so subjective that mfrs don't want to incorporate them.

to expand on Donna's suggestion:

Goosefeet Gear (Ben Smith) has a stuffsack down pillow listed on the website, sized to insert the Exped UL Large.
I wanted one for the Exped UL Medium, which Ben made for me in custom size last year.
The size to fit the Exped UL Medium perfectly was 14" x 18". I also requested both ends open & cinched – cinching both ends gives a snug fit around the Exped and keeps the down where you want it. Very comfy.

And a simple alternative:
A standard sized "Buff" fits perfectly around the Exped UL Medium as a pillowcase, with room to stuff clothing in there. If the temperatures are such that I'm likely to be carrying a down jacket, but unlikely to be wearing it at night, stuffing the down jacket inside the Buff on top of the Exped is ultra-plush.

Necessity is the mother of invention. All great ideas. I particularly like Ralph's idea of using the Exped pillow, buff, and down jacket in concert together.

There must be a business reason why Exped doesn't make a down-filled pillow particularly when the same products used to make the mattress would be the same products used to make the pillow. Call me crazy.

From the looks of it, the Exped pillow is heat sealed with a die. In other words, both pieces of fabric place under a form that that is the shape of the pillow and then they are essentially stamped (with heat) together. Trying to add down would probably not be optimal based upon the design.

I would think that the best design would be like the Cocoon Air Core pillows only with a down outer layer, like Goosefeet is doing with their Exped Stuff sacks. Stuffing the down in the air chamber, although it would provide insulation, wouldn't be as comfortable as the down on the outside.

I just got the new StS pillow – Aeros Ultralight. It's a similar size and shape to the Exped UL Medium, except that the Aeros is much thicker – 1.5-2" thicker I'd say. As a side sleeper who needs good head support, I'll definitely be switching. The surface is also better — rather than just the plastic, it has a slightly plush coating that I think will be ok to sleep on without a cover. I'll still generally use my Buff as a pillowcase, though – the Buff is either on my head as a balaclava (if cold), or around the pillow, so either way my head's not directly on the pillow.

on my scale,
Exped UL Medium – 1.6oz
StS Aeros Ultralight – 2.0 oz

Aside from the thickness of the pillow and the plush coating on one side, the construction is almost identical – I'd guess that these are made in the same factory.