Believe it or not, I did quite a bit of research on these. I had one that was way too complex for my needs; I want it primarily for my iPad with the Logitech keyboard. I didn't want bulky, and I didn't want cooling fans or beanbag pads. I use it folded in half and propped open a bit to tilt the iPad back, and it's perfect. I'm an author, and I put a lot of time in on the keyboard, so I know what I'm talking about.
Have taken this on a few business trips, and it meets my requirements: portable, light weight, functional lap desk for travel. The mousing surface is a little small, and the surface scratches easily, but it does the job.
The Targus Compact Laptop Desk allows you create a workspace for your laptop wherever you go. Nearly as thin as a magazine, the Compact Laptop Desk folds in half to easily fit in a laptop bag for travel. The desk lays flat on your lap for a stable work surface, ideal in airports or other compact spaces where a table is not available. The Laptop Desk features two surfaces that are positioned for left or right handed mousing. For added convenience, the desk also converts to an adjustable stand to provide an elevated, ergonomic tilt when using a laptop in a variety of environments including classrooms, coffee shops and airplanes.