Two general items up front: 1. Restricted free agents aren't real free agents. Anyone worth keeping will receive a high tender (1st and 3rd round, 1st round, or 2nd round picks as compensation) and it won't cause any salary cap problems in an uncapped year. "Teams have the leverage." Other NFL teams aren't going to offer a big contract and surrender a high draft pick. 2. The best thing the Green Bay Packers could do in free agency is resign all their current free agents.
This is an easy area to discuss because there are no free agents at either position. Walter Football listed TE Spencer Havner as a restricted free agent, but that's not what I read, and I'd expect he's an exclusive rights free agent. He's certain to receive a contract offer, and he'll have no other choice but to accept it.
If the Packers were to sign a free agent at either position, I'd suggest the same player I mentioned in regards to the special teams: Chargers Pro Bowl (as a special teams player) WR Kassim Osgood. He could be used as the No. 5 WR, and he may even challenge WR James Jones (ranked way down at No. 58 in 2009 by Football Outsiders) for the No. 4 job.