Link: http://sports.espn.go.com/nfl/news/story?id=2289987

Well, not many people saw this coming...a week or so after the Bills fired Tom Donahoe, re-hired Marv Levy and dismissed 5 assistant coaches, Mike Mularkey has apparently resigned as head coach.
While Mularkey had endured a lot of criticism at times in the season, he seemed to have weathered the immediate demands for his dismissal. However, the ESPN article suggests that Mularkey concluded that the way that the Bills were being re-structured would make it impossible for him to be successful. There was also a suggestion that part of the resignation was for family reasons.
One wonders whether he has an inside track on another coaching job. His resignation is superficially a highly principled act, and/or one that will free him to rapidly get another coaching job.
By resigning, he may have forfeited the remaining money on his contract, which still had 3 seasons to run. One reason why NFL coaches usually end up being fired is because they usually have the remainder of their contract paid off if they are dismissed (which is different to players' contracts; nearly all players can have their contracts terminated at any time without the club owing the player any more money).
This is why Steve Mariucci is unlikely to coach anywhere next year. He will essentially be paid close to $5m by the Detroit Lions to do nothing. Unless, of course, he wants to coach the Bills...