They have an interesting twist on business class...

On the MD80s (these are the 'saver' aircraft with standard 3x2 coach seats) they have added a business class section of 12 seats. You can only reserve it in advance through a travel agent as a business class fare. Otherwise, they open the seats up to buy-up for $60/segment at 24 hour checkin.

Don't know when it was implemented, but interesting derivation of the NW Coach Choice concept.