I don't really want to write a full article, so just a quick idea. Nate McLouth has been Atlanta's primary center fielder this year. He also has an OPS+ of 91. Meanwhile, the last place Astros have center fielder Michael Bourn, who is under contract through 2012 and has an OPS+ of 117.
According to MLB Trade Rumors, the Astros want pitching prospacts. I don't know a lot about the Braves' farm system, but I'm pretty sure they have two to three good young pitchers (if I recall right). This seems like they should match up pretty easily, right?
My off-the-top-of-my-head calculations say this would be a 2 WAR upgrade for the Braves the rest of the season (using Fangraphs). And it would help the Astros to rebuild. Maybe the Braves don't want to try and upgrade, seeing as they're running away with the wild card? But they're still talking about trading for other players, according to MLB Trade Rumors (including fellow Astro Hunter Pence).
I don't know. But this seems like an easy match-up.