I would very much enjoy having Turner Gill come back and would have enjoyed him as HC or OC or QB coach.
I would also have Ron Brown back in an instant. He was a fine coach (he could likely coach many positions. He would be a fine HC in my view but he has never really wanted that extra heavy load of duty.
I would enjoy George Darlington back but am sure he has aged out of the ability by now.
Keven Steele was a superb recruiter and excellent LB coach. He'd be welcome back I am sure.
Mike Minter was an superb player and I am confident could contribute a great deal in the secondary. Not sure if he is coaching though.
David Humm was not a 'coach' as far as I know but after many years in the NFL with the Radiers, he could certainly offer some great advice. I bet he could call plays with the best of 'em.
Charlie McBride is still able bodied enough to help get those Blackshirts lined up right to stop those pesky 'fun N gun' offensive schemes. Of course he wants the fastest, meanest, hungriest 11 guys on grass.