I found an interesting article (from a Cowboys fan) on how the rest of the league should learn from Marvin Lewis and Jay Gruden on 4th down.

http://bit.ly/VE3BR0

The Bengals have gone for it on fourth down on 12 occasions in the first half alone this season. Those 12 plays above have increased the Bengals’ expected points by 2.43 per play. That is nearly and en extra FG in the first half alone every game this season.

Marvin Lewis gets a lot of flack from Bengal fans who have been tired of accepting mediocrity from the franchise. However, an outsider's perspective seems to indicate that the Bengals are ahead of the curve (at least in terms of the cajones to go for it on 4th down in situations that they aren't forced to).