Ryan's written a great article on the Green Bay Packers two possible franchise tag targets. I don't expect either player will receive it, and I had couple of points to add. For another resource, Mac's Football Blog has an excellent break down on the cost of the franchise and transition tags for each position.
It looks like Crosby would cost about $3.2 million for the franchise tag (transition is around $2.9 million). Ryan points out Crosby's inconsistencies on field goal attempts, but I also blame him, in part, for the poor kickoff coverage. He only had 4 touchbacks on 84 kickoffs. That was one of the lowest percentages in the league. Compare that to K Billy Cundiff, who just received a five-year, $15 million contract, who had 40 touchbacks on 79 kickoffs (50.6%). There's no way that Crosby should be paid like Cundiff.
DE Cullen Jenkins is the name most frequently mentioned. I think it's a no-brainer that the Packers would like to keep him. But his tag will cost either $11 or $13 million, depending on whether he qualifies as a tackle or end. He's worth it, but their cash flow might not allow them to pay it. I do have some injury concerns going forward, but no more than I have for any other player.
There's no one else hitting free agency worthy of a tag other than those two. The tag for WR James Jones would cost around $10 million, and he's not worth that kind of money. Here's the complete list from JS Online.
Teams have until February 23rd to make a decision. CBS Sports has a good franchise tag tracker.