Five words: Ray Edwards and Charles Johnson. Because the Vikings are using that franchise tag on Greenway, they won't be able to use it on Ray Edwards, who is likely to be the prime pass rusher on the free agency market in 2010. While there's still the possibility that Edwards will face some other sort of tag, that all depends on what kind of tags will be available in the new CBA. And it seems unlikely that any tags will be added in the new CBA. Furthermore, Jason LaCanfora has reported that the Vikings aren't real interested in re-signing him. So when all is said and done, he's likely to hit the market, and he should be a target for the Bucs.
Ray Edwards fits the Bucs' current free agent profile very well: he's still young (only 25) with his prime years likely ahead of him, and he plays at a position of need for the Bucs. However, there are certainly some reasons not to spend a lot of money on the man: he's played next to the Williams Wall, which has certainly helped his numbers, and he didn't start producing a lot of sacks until Jared Allen got to Minnesota. And even then, he only ever got to 8 sacks with all that help along the defensive line. There's reason to believe that he won't be any better than that with less talent around him. This would mean he'll basically be a good left end at best, and a replacement level player at worst. That's not a great return for the premium contract he is likely to get. Still, the Bucs will have a lot of cap room to fill, and even a solid left end with some pass rush skills would be a massive upgrade for the Bucs.
Charles Johnson is in a similar situation. However, he only has 4 years of accrued season and it's more likely that he'll be a restricted free agent instead of an unrestricted one. That means that the Panthers are likely to tender him, and the Bucs would have to give up draft picks to get him. Of course, that's only relevant if restricted free agency returns in the CBA, and if players with 4 accrued seasons will count as restricted free agents. Still, Charles Johnson is perhaps a more intriguing prospect than Ray Edwards because he's coming off what you could call a dominant season. With 11.5 sacks he was the 7th most prolific sack artist in the NFL last season, after seasons of 6 and 4 sacks respectively in 2008 and 2009. Like Ray Edwards though, he did this from the left end position. The fact that he only has one year of sustained production should mean he will come at a lower price than Ray Edwards, but that of course also means he carries extra risk. He could be a one-year wonder, or he could simply stop playing hard after he's rewarded with his big contract. But unlike Ray Edwards, he didn't have the advantage of playing next to dominant players. He's also a year younger than Ray Edwards, and would fit the Bucs youth movement perfectly.
These two are therefore players to keep an eye on once the CBA is agreed upon. The Bucs are building through the draft, but the need at defensive end is so great that they could easily look at free agency too. Then again, we could've said the same thing about defensive tackle last year.