"Waterfield":http://sfbags.com are ex-bike messengers and make custom bags in San Francisco. Expensive, but checkout the Sleevecase which is a totally custom holder for a laptop. Perfect for my minute Sony TR-140 for which common laptop bags are just too big.
!>http://www.sfbags.com/products/sleevecases/images/prod_sleevecase_detail_2.jpg! to see how well made they are. Rather have one good bag than a zillion giveaway IMHO.
Another great bag is the iPod case. It is the only one that I've found with a belt loop and which also lets you use the dock easily plus it holds your headphones too. They have another version for holding the Altec Lansing InMotions and also a general junk bag. Check them out.