Tell me about your seat cushion you can't travel without!

I use to put a sleeping bag on the jackknife sofa. It made sitting and sleeping much more comfy. For the car seat, I bought one of those "As seen on T.V." cushions. It was made like a sandwich with two layers of foam, and a layer of jell in the middle. Very nice, sorry I can't think of the name. I own a Lincoln MKZ, and you'd think it would have a comfortable seat-no way- it's horrible. My wife wants me to trade it, and she's never like that. I talked to the local seat expert in town, and he says they make the seats hard so the sensors etc will work right. When I was young, I could sit on anything, not so now that I'm older.