I know it's been discussed here several times before, but like the OP, I'm not going to both searching.
I have 2 (shows how often I fly int'l C/F). I use them to store all of my little travel acessories - chargers, USB hub, mouse, etc. They fit neatly in my laptop bag next to my iGo charger bag and a paperback or two.
LH has those drawstring pouches, which I sometimes use on longer flights as my "stuff to keep at the seat" bag - usually before the flight I'll put my iPod, earbuds, a book, a couple of crossword puzzles from the previous days of the paper, a pen, and any drugs I'll need if I'm ill/need to sleep. When I get to my seat, I can just grab the small bag out of my carry-on, put my carry-on in the overhead, and I'm in my seat and out of the way of everyone else.