Actually, your suggestion sounds great! Probably use a daypack anyway, so the cube will go nicely, and I have a few. The old AA J cabin little zipper pouch things are ideal for gadgets.
Cheers.
90% of the time, my "purse" is a daypack, too, especially when I go to work at the ski area or I'm travelling :-)
I try to reuse/recycle the old bags and stuff I have. I do like to compartmentalize my junk when I travel - it makes it easy to know which little bags I have to drag out for the TSA folks, and it's easier to find than rummaging through one big mass of stuff. My Eagle Creek cube can hold my Acer power brick, my little power strip and different adapter plugs. I have another one that carries my on-the-airplane goodies - igo adapter and my noise isolation earphones. And, one more for my rechargers for my Ipod, Razor, and Nientendo DS. I get far fewer bag checks at TSA than I used to when I carried a jumbed mess.