Well, I have gotten my mini-bag for airline travel, and it only has one problem, which I expect to fix soon. Here's the bag.
http://www.solocases.com/item.aspx?id=1577
It's big enough for a EEE PC 1000HA, But I put in a smaller 901HA, and had enough room for part of the ac adapter in the computer portion of the bag.
The bag expands from 4 inches (10cm) to 6 inches full, just by relaxing the strap holding the fold between the two section together. (it unfolds butterfly fashion, for airport screening.)
Here's what I've put into it comfortablely, so far.
EEE PC 901 HA
power cord and inverter for EEE PC 901 HA.
BEBook reader with custom leather cover
Panasonic mini videocamera (Standard Definition version, using SD chip)
Power cord and inverter for video camera
2 - 2.5" external hard drives.
USB cord for external hard drive.
Creative Designs - Zen Media player MX (with belt case)
USB charger for Bebook and Zen MX player
Zipper case containing 14 SD chips.
Missing or no room,
Sony noise canceling earphones. I knew I couldn't pack them when I started. They fold up into an egg shape, 10 cm x 12cm (4 inches by 5 inches). they go in the side pouch of the clothes bag, where they've always gone.
Mini Mouse - on order, but not yet received. I'll see if I can fit it in.
It has a nice padded over-the-shoulder strap as well, which you can unhook one end when you sit down and hook it to the seat back pouch in front of you. You then slide the bag under the seat in front, and if you want to get at it, just pull it up by the strap.
Now for the problem. The computer portion of the bag has sides the go all the way up to the top of the bag. The front set of pockets do not go to the top. There is an open gap of 4-5 CM from the sides to the top. Small things could fall out. I am going to solve this by buying lengths of Velcro and having my sister sew them on the sides, so they overlap the open top of the front compartment, keeping thing from falling out.
Other than that, well constructed and handy. It's small enough that TSA will not mistake it for second bag, and will carry my stuff.