Well, in my opinion-and I have been wearing them for years-Birkenstocks have been using the "bare feet health" concept for years.
But-I cannot stress this enough-they have to be REAL Birkenstocks, and not the $9.99 Wal-Mart/Payless Shoe Source "looks like Birkenstocks" knock offs.
Birkenstocks come in regular shoes as well as sandal styles.
In an athletic shoe, the Nike Free use a very similar technology. At the fitness store I go to, they actually tell runners who are new to the Free shoe not to go out and try to run their usual 1-2-10-whatever miles in them at first, but to start slow and build up-because they are now working underused foot muscles.