Among them and that have been identified so far?
Brian Gaine of the Dolphins, the former GM of the Bears Jerry Angelo and Omar Khan the chief capologist of the Steelers. UPDATE: Seattle capologist John Idzik as well as Jim Popp of the CFL's Montreal Alouettes
Angelo is a longtime front office member, most recently of the Bears (2001 - 2011) and the Bucs (1987 - 2000) where he helped turn teams around and get them into playoff contention. Angelo left the Bucs due to new ownership of the team after building a playoff caliber team built on defense and hard-nosed offense. In Chicago, Angelo built teams that went to the Super Bowl, but fell on hard times and was fired in January 2012 when questions about his coaching hires, drafting, trades, and free agent signings weren't bearing enough fruit to keep pace with the resurgent Packers.
Omar Khan of the Steelers has been a GM candidate often recently and is praised for his skill with the salary cap. There's some eerie similarities between him and Tannenbaum. Khan is relatively young, just 35. Tannenbaum was 36 when he took over the general manager spot in 2006 at age 36. Ironically, Khan attended Tulane for his undergrad degree ... the same school where Mike Tannenbaum got his law degree. Khan has done a great job for years with the Steelers as their key contract negotiator, but the concern of course around him is that he might have a similar skill-set to that of the Jets former General Manager. Khan seems like more of a numbers guy than evaluator of personnel. In that case, Khan might need to heavily rely on others to help him find the right players, and that seems to be how the Jets are now in their current predicament. But with real cap problems as they head into 2013, would a cap guy be the right person to see them through?
John Idzik is the VP of Administration in Seattle and while he has the administration and cap background he has deeper roots in player development and even some coaching. Idzik's father actually worked for the Jets many years ago. Idzik's name has been mentioned in relation to the Cleveland opening, but nothing beyond that. Idzik's responsibilities in both Arizona and now Seattle have been varied and seem to indicate that he might be a competent manager while also possessing some of the requisite appreciation for both numbers and personnel.
Jim Popp is an unconventional candidate, but one that seems to have garnered a lot of attention recently and had an amazing run with Montreal. Last year he was seriously in the mix for the Colts job and this year it was the Panthers who came calling with the blessing of Ernie Accorsi as well as the Jaguars.