On to the starting rotation. Kyle Davies has lost tons of value this year and I doubt anyone will bite unless they want to take on the KDP*. Brian Bannister has to intrigue several teams. I think he would be a great addition on a team seeking rotation help. The Yankees look like they need some help in their rotation, Sabathia could miss some time and Wang looks lost on the mound. Interesting returns could be CF Brett Gardner. Luke Hochevar is doubtfully being shopped, but he could have a high return, as teams usually don't like parting ways with 1st round picks on the ML roster. But I would be interested to see what some teams would be willing to part with for Hoch.
*Kyle Davies Project
Offensively, I would expect Mark Teahen to be high on a lot of teams' lists. The Cardinals are dying for a 3rd baseman. Would they be willing to part ways with SS Brendan Ryan? Ryan has had a great year (.308/.346/.411) and is pretty savvy with the glove. Miguel Olivo would probably interest most teams looking for a catcher with some pop. The Giants could be interested as could the Brewers. David DeJesus has to interest several people who are looking for OF help or even looking for a 4th OF.
Jose Guillen is a problem. He needs to be moved. Shouldn't be too easy though, unless a contender is looking for a malcontent who fields poorly, strikes out too much, has lost almost all of his power and can't run for $12 million dollars. If Guillen is moved, the Royals will have to eat a majority of his salary. $5-8 mil is my guess. He'll most likely be used as a bench player/4th OF in the NL, and a bench player/DH in the AL and I don't think too many teams would be willing to pay $12 million for that.
Either way, it should be a fun July as far as trades go!