There are presently a few cases for the Aero.

The Wetsuit 3.0(tm)
     This case seems to have the best fit for the Aero. This is a case made of
     wetsuit material. It is water resistant, has a screen shock protector, and
     has a zipper at the base for easy access to the ports on the back of the
     Aero. It has a small zipper pouch in the front of the case, which can hold
     the floppy drive OR the power supply. It has carrying handles as well as a
     shoulder strap. This case is zipper closed.

Targa(tm) Cases
     Targa makes a small case for laptops, and this one will hold the computer,
     the power supply, the floppy drive, and a few extra components. It has
     pockets on the outside, inside, and has a zippered closure. It also has a
     fair amount of padding.

Compaq(tm) Case
     A black vinyl bag which fits primarily the Aero. One pouch on the inside
     is suitable for a stack of papers. No provision to use any ports while the
     Aero is in the case. It's nice and small but not meant for hauling
     accessories around as well.

Micro Center(?) Case
     This is a black leather case (well, sort of leather looking). I believe it
     is made by MicroCenter, because it has "WIN BOOK" on one side of the case.
     It is fairly small (smaller than most of Kensington cases). I can fit AERO
     (or a 6-lb notebook), AC adapter, mobile expander, floppy driver, and some
     cables in it. Two compartments. It is not as good looking/sturdy as
     Kensington's cases, but it costs only $20.00.

Do-it-yourself
     Here is an idea for a cheap case for the Aero: A nylon covered, padded 3
     ring binder from Mead for $10. Line it with some 1/2" foam cut out for the
     Aero and it's power brick and floppy, and away you go.