The Jacksonville Jaguars have done some work on their defensive line in free agency, but the interior of their offensive line still needs quite a bit of work. The team did lockup Zane Beadles as their starting left guard of the future, meaning the left side of the line with Beadles and Luke Joeckel is theoretically locked up.
There's still massive holes to fill at the center position and at right guard, one of which is likely to be addressed in free agency in the form of a veteran.
The center position in particular would seem to be the most likely to upgrade that route, but the options are quite limited looking at what's available. The best player on the market is Alex Mack, but as I reported earlier the Jaguars don't seem to be in the running there. They can afford it, but it's still a massive investment.
Outside of Mack, the best fit in my opinion would be Evan Dietrich-Smith, who's taken a visit with the Tampa Bay Buccaneers but hasn't had much traction outside of that. He's experienced in a zone blocking scheme, loved by Aaron Rodgers and was Pro Football Focus' eighth rated center in 2013. He just turned 28 years old, so he's still right in the range for the age of a free agent you want to sign to a longer term deal.
Brian De La Puente is also on the market, but I'm not familiar enough with the New Orleans Saints blocking scheme to say if he's a fit or not, but he's been kind of a mediocre player outside of one season. He's 29 years old and hasn't seemed to generate very much interest so far.
The Washington Redskins recently released Will Montgomery who has graded out well the past few years, especially in the Shanahan zone blocking offensive scheme. At 31 years old he could be a stop-gap type of player if the Jaguars plan to draft a center in the mid-rounds to develop.
New England Patriots center Ryan Wendell has been another popular name that people have brought up, but in 2013 he was one of the worst centers in the NFL graded by PFF. However in 2012 he was their fourth best graded center and graded out decently in 2011 and 2010 playing guard and center on spot-duty.
The two most likely moves in my opinion are Montgomery as a stop-gap or Dietrich-Smith on a four year deal around $4.5-6 million per year.