I liked this analysis of the NFC North's salary cap situation by Kevin Seifert. The Lions salary cap problem (only $736,000 available) is a result of the old salary cap rules. High draft choices are supposed to help bad teams, but they also created a different headache. From ESPN:

In 2012, Johnson ($18.5 million), Stafford ($16.1 million) and defensive tackle Ndamukong Suh ($12.2 million) would account for nearly 40 percent of the Lions' cap space under their current contract terms. For that reason, it seems almost certain that Johnson will have a new contract if he is a member of the Lions next season. 

The Lions have little chance to win without those three players, but they shouldn't cost them 40% of their salary cap either. Those weren't bad contracts. That's what it cost to sign the No. 1 and No. 2 overall picks in the years that they were drafted. 

Further down is a discussion about what the Green Bay Packers can do with their $12.8 million in salary cap room. From ESPN:

The Packers could approach guard Josh Sitton, tight end Jermichael Finley and/or punter Tim Masthay.

I never thought I'd see Masthay mentioned in the same sentence as either Sitton or Finley. What do you think of giving those players an extension?