Another case that works is the D-Res 8. The width and height are perfect, and there's a pocket in the back for a memory card. Since it's deep enough to hold my Canon S30, it can hold the Axim, my spare battery, and headphones all at once. Alternatively, I managed to fit in the Axim and the huge plastic case that my Linksys WCF12 Wifi card came with.
If you like to carry credit cards in your case, then they'll fit in the memory card pocket. However, I'd prefer to buy a cheap billfold that fits in the case, so that I don't have to fumble around to get at the credit card.
Only thing I wish is that it had a more secure beltloop. The larger LowePro beltcases have a double-Velcro loop; you slip it over your belt, attach the velcro, and then swing up a second piece from the bottom. It's extremely secure (but not quick to remove).
http://www.lowepro.com/pages/series/dres/dres8.htm
Still, I think I'll have to check out the D-Res 100. I've got to have something for my camera...
Russ