The Western Flyer from Tom Bihn is a small duffel/backpack conversion travel bag designed for quick trips or minimal travelers.
Other Bags to Check Out:
The Travel Bag from Nomatic is a solid offering in one bag travel.
The Aer Duffel Pack is not the tool for every job, but for particular uses it just might be perfect for you.
An extremely versatile and feature rich bag that doesn't look half bad, the Errant has lots of organization in an innovative pack for everyday use. One of my favorites.
A very well designed, stylish travel bag for one-bag travel with enough pockets, organization and access to make travel smooth.
DSPTCH hand-makes bags here in the USA and the Travel Pack is a great example of the kind of extremely durable designs they put together.