I second the weighted bookmark. I've got mine over 12 years ago, and is very worn. I even use it to hold my sudoku puzzle books and magazines open. I got stopped at airport security because they couldn't identify it. It was scary at the time, but funny in retrospect.

I also have a lap desk, beanbag type bottom, hard top (leather like). And most importantly raised edges, so stuff won't roll off. I use to hold my books and meals etc.. Dad got it for me for xmas. It came in handy after my ankle sprain and spent my waking hours on the couch.