I just wanted to get a little front page love for Bloguin's site dedicated to the NFL draft. As you know, I'm no draft freak, but for those that are, this is a great page to check out. You might want to use their breakdown of the Colts as a starting point:
If the Colts were going to target players on the interior of the defensive line they may go after a player like Penn State DT Jared Odrick or DT Brian Price from UCLA. Both players have the interior presence the Colts like, they're quick and explosive enough to attack the gaps as is needed in the Cover-2. However they're big enough to help hold up against the run thus putting the Colts in a better position to stop the run.
Beyond the trenches the Colts could also target players in the secondary to offset the loss of Jackson and Jennings. Meaning CB Kyle Wilson from Boise State, Kareem Jackson from Alabama, or Dominique Franks from Oklahoma could also be options.
As always though as analyst I'm limited to guess work in the case of the Indianapolis Colts. They may completely surprise us all and take a player that doesn't seem to fit into their immediate needs. Trying to project the Colts in the draft is like trying to predict what the weather will be like in two weeks.