Here's a good salary cap article at Football Outsiders by J.I. Halsell. It's especially interesting because it points out who is available in a trade based on the contract tendered to them as a restricted free agent:

When looking at where players have been tendered, keep in mind that these tenders tell you how much a club values a player. For example, in lieu of giving running back Cadillac Williams the more lucrative first-round tender or first- and third-round tender, the Bucs chose to extend the original-round tender, which is for less money and would only give the Bucs a second-round pick if he were to leave as an RFA. The tea leaves tell you that the Bucs are willing to part with Williams.

He lists six restricted free agents who fall into this catagory: DE Darryl Tapp, DE Marcus Spears, WR Brandon Marshall, OL Alex Barron, RB Cadillac Williams, and CB Carlos Rogers. Also, with the exception of Tapp and Marshall, who were both drafted in 2006, they were all drafted ahead of QB Aaron Rodgers in the 2005 draft. 

Shortly after Halsell's article was published, Seattle did actually trade Tapp to the Eagles for DE Chris Clemons and a 4th round pick. Over at Field Gulls, they are not putting a smiley face on this trade. The John Schneider/Pete Carroll era doesn't seem to be getting off to a good start.

Would any of these remaining players interest the Packers?

Spears. At best, he'd be the 5th lineman on the Packers's 3-4 defense. Plus he's looking for a new contract similar to former teammate DE Chris Canty, who received 6 years, $42 million from the NY Giants in 2009. I can't see why they would make a trade for him.

Marshall. Does he have the most baggage of any player in the NFL? I doubt the Broncos would accept less than a 1st round pick for him. Plus he'll want big money for a long-term deal, or the Packers would risk losing him after 2010 (depending on the next labor deal). And there would be negative PR after WR Donald Driver is moved to the bench prematurely. Pass.

Barron. While there's no truth to the rumor that they plan to name the false start penalty after him, he does have some value as a league average right tackle. If the Packers hadn't signed RT Mark Tauscher, a trade for Barron would have some merit, but it doesn't make any sense now.

Williams. I'm not sure he can do anything RB Ryan Grant or RB Brandon Jackson can't do. He'd come at a very high price for a potential 3rd string RB. 

Rogers. I don't think the Packers should trade for him, but he's a better option then the previous four players. Over at Hogs Haven it appears they think Rogers is a good tackler who can get beaten deep and can't hold onto an INT to save his life. He's not a bad player, but he has never lived up to expectations and the Redskins probably wouldn't take less than a 3rd round pick for him. At that draft position, the Packers might be able to find someone just as good.

Are any of these worthy trade candidates?