The Eagles have the biggest coaching staff in the NFL, with 24 members. This data comes from an ESPN report. Jason over at BGN broke it down and offers some good analysis.
Things like this are what make me shake my head when some angry fans accuse Jeff Lurie of being cheap. He spends money wisely, not just to spend it. You are better off to spend on a scouting staff and coaching staff than to throw huge money at free agents.