Perhaps you've already seen John Clayton's item on salary cap space for all 32 NFL teams. If not, I've pulled the four NFC North figures into this post.
Keep in mind that cap numbers are fluid this time of year and aren't finalized until shortly before the free agent market opens in March. But for now, you can a least have a general impression of whether your team is in great shape, big trouble or somewhere in between. (This division finds itself mostly in the latter category.)
Ordered by available space:
Minnesota Vikings: $16.1 million
Chicago Bears: $13.3 million
Green Bay Packers: $7.1 million
Detroit Lions: $(-) 1.1 million