The Philadelphia Eagles recently released WR Jason Avant. I could see the Colts going after him. Obviously, the Philadelphia connection means that Grigson is familiar with him. The Colts have a ton of cap space if they don't go after the big name(I don't think they should) then Jason Avant would be a solid veteran to add to bolster the WR core. He wouldn't be too expensive either. The Colts could probably get him for a deal similar to what they gave to Darrius Heyward-Bey.
The elephant in the room is definitely Reggie Wayne's knee and will he be able to get back to %100. The Colts were able to win games without #87 so there's no reason to rush him back. I don't think Reggie Wayne will even be %100 by the start of the season and Jason Avant could fill in his absence or provide veteran depth. He's very similar to Reggie Wayne in that he relies on his size, good routes, and good hands to be effective.
It'll be good to see him in Colts blue.