WHen traveling with my n810 I always use a nice small LowePro camera bag, it fits perfectly and has a little pouch on the front for extras (battery, headphones etc. As well, it clips nicely to a belt and doesn't take up pocket space.

It's not 'executive' and it is perhaps a little bulky for a 'case' but it works, and it's nicely padded for those little incidents. It's been very useful since I use the n810 exclusively as my travel device (no laptop) and aim to do the same with the n900.