In the spirit of [Toni's recent "sermon" on SHARING] ... here goes nothin'.
My wife has been asking for something that would make it more comfortable for her to read & write in bed. We have a very simple waterbed frame with a (pair of) Select Comfort air mattress(es). The somewhat-attached headboard has room for a row of books (or whatever) but it's not comfortable to lean against.
I'd been thinking about what I could do ('cause I really stink at flatwork at this point), and I finally started working on a back rest on Christmas Day. My wife didn't know what I was up to until I offered her a "preview of her surprise". (I asked her to test drive the back rest while it was still in 3 pieces and give me feedback on the angles, etc.) She was pleasantly surprised, and "approved" the design, so I persevered.
Anyway, here it is so far. The "backboard" is about 16" x 22", and the lean angles are 35 degrees and 55 degrees.
It was a nice follow-up to our Amazon.com, pick-from-my-wish-list-and-I'll-pick-from-yours gift exchange. She has used it a few times, and says she really likes it. Who am I to tell her about the missed opportunity for half lap joints and something better than hardboard? At least I did a 1/8" roundover on (almost) all edges with my Colt, and sanded things up nice.
She did ask me to add a "handle" to make it easier to pick up ... something like an oval hole near each end of the backboard. Gotta remember to do that....