I'm not sure that it's been linked to before here, but if anyone's looking to mess around with the cap numbers and see what teams can and cannot do, Shamsports Capulator is excellent.
http://www.shamsports.com/capulator
Select a team, then start resigning/renouncing guys to see what's possible for different teams. Note that the trade function doesn't restrict by forcing you to match salaries (like ESPN's trade machine), but beyond that it's really good.