I would make Holt available to see if he can help bring back a coveted young SP that the Red Sox are so desperate to add. The Mets would be interested in Holt, no doubt about it. Unfortunately, the Mets aren't trading any of their top young arms, and they certainly won't move one for Holt. Holt is good, but he isn't good enough.
The Royals sent down Ventura. Vargas, who just returned, left the game early with an elbow issue. The Royals could be in the market for two SPs, a top-of-the-rotation type and a middling type. You want a middling starting pitcher? -- come shop with the Red Sox, they have middling starting pitchers. Cherington should offer the Royals Miley, maybe the Royals will bite and part with a top prospect.
The other two players with trade value would be Uehara and Tazawa. Napoli isn't worth anything and the Red Sox don't seem interested in playing him anymore to build up his trade value. Victorino is useless. I would trade Hanigan, just to get his contract off the books for next year, but he is essentially worthless too.