You may have seen those interesting floors at REI – floors that look like mulch pressed into a floor. We decided to use that in our house; we like how it looks, it adds interest in, it looks like mulch (which we loved) and because it uses scap, it is quite environmentally sound. Plus, it is inexpensive, and will serve as a great subfloor if we ever upgrade. We used Bona for sealing our OSB (originated strand board) floors .
We loved how it turned out. Eventually, we might get cork floors, but in the meantime, who can beat $10/a sq foot for flooring (OSB plus sanding/sealing expenses!) A little about the very environmentally friendly sealing system we chose after some research: