From the looks of your lineup, it seems like you're in a pretty good league so it might be difficult to find some waiver players.
If Ryan Doumit is available pick him up. He will be a big upgrade at catcher when he returns off the DL.
As for pitching, Pedro Martinez or Chris Carpenter might be worth stashing on the DL. I'd pick up Pedro asap. José Contreras could be worth a look for a few more games. Who all is available as free agents?
Since this post, I have dropped Dana Eveland and Brad Hawpe, picked up Chris Carpenter and stashed him on the DL. (Pedro was already gone, and besides, I really don't trust him that much at all, I don't think he's even going to be that effective this season). Someone in my league dropped Ted Lilly, and I'm going to use my #5 waiver pick to try and hopefully pull him.
Brett Myers is also available on FA, dropped as well. But I'm leaning towards Lilly. Contreras and Doumit are both gone :(
I might have to stick with my catcher unless you guys think these options are better: Miguel Olivio Gerald Laird Yadier Molina Kurt Suzuki Kenji Johjima
I really like your team, I think if you kept it as-is, it would be a contender all year. I may try to package a weaker starter (Harang/Harden) and maybe Jermaine Dye for a better starter like a Sabathia (who will get hot) and pick up a OF for Dye, or just wait for Hawpe to get off the DL. I'd also think about picking up Johjima for Navarro, but I think they're pretty equal.