Buy or Sell - NL CENTRAL
St. Louis - Buy or hold
Needs: St. Louis just acquired Jeff Weaver, an innings eater, to help bolter the rotation, but really needs Mulder to return healthy as the #1 starter. The bullpen has been plagued by inconsistency or consistent mediocrity - including from their closer, Jason Isringhausen. The production from 2b has been lackluster and could certainly use a boost if someone hits the market. They could stand for a catching upgrade, especially if it adds some pop (which could use some bolstering) to the line-up.
Chips: The Cardinals have received decent production from back-ups such as Hector Luna and John Rodriguez and could use that depth to upgrade a starting position. However, other than pitching, the Cardinals don't have any deep needs that justify weakening some other aspect of the team, so I really expect them to hold and maybe make a few waiver claims or small trades using bit MiLB players to acquire a role player for the big club.
Cincinnati - Buy
Needs: Like every team, the Reds could sure use some pitching. Arroyo has over performed and one has to wonder if he'll fall back to Earth as teams become accustomed to him. They really need an upgrade to the 4th slot and a 5th starter. Acquiring Guardado was a smart, low-risk move for an awful bullpen in dire need of assistance. The Reds could use more production from their 3b, and a boost from SS and Catcher.
Chips: The Reds don't have a particularly strong farm system, but could use their OF depth to improve the team if they really want to be a serious contender. Freel is a very solid back up, and Kearns, Dunn and Griffey Jr. are always thrown around as trade possibilities. Homer Bailey (P) has been stellar for Chattanooga (0 Earned runs in 17.0 innings), but should be off limits for all but the best available talent (Willis, Zito?). OFer Jay Bruce is doing really well for Dayton, but other prospects have struggled in 2006.
Milwaukee - Buy or Hold
Needs: Milwaukee is in a weird place - they need to get hot to make the playoffs, but they aren't really a seller, so I expect they'll make some token moves, but nothing that will put them over the edge. I know, it's like a broken record - they need more pitching and a consistently healthy Ben Sheets to pair with a solid Capuano. The rumor mill has Milwaukee inquiring about old-timer Maddux - only a puddle-jumper away in Chicago. Rickie Weeks has been a great help as a hitter, but is incredibly weak as a defender, but probably won't be traded because he's young; likewise for the currently injured J.J. Hardy at SS. The bullpen is terrible
Chips: For the most part, the Brewers won't part with more than a 'name' player who is underperforming (BP guy?) and some token minor leaguers because this is a team that finally has a direction and the players ready to take the reigns (Fielder, Hardy, Weeks, Clark, Capuano, Sheets). Veterans who could be moved include Cirillo (though that will weaken the team) and Jenkins. Strongest bet to leave? Carlos Lee has drawn some interest because of his strong campaign and is probably their most valuable available chip to improve the team for the long-term.
Houston - Buy
Needs: Unless the Astros have a huge drop in the standings, they'll buy because the core of this team is getting older and their window is vanishing quickly. They should be able to get by with their pitching, but they REALLY need hitting (Roger, don't you wish you went to Boston?). An easy way to help would be some power in the meager OF. The Astros should be playing Lamb more than Ensberg at 3rd. Ausmus seems like he's more suited to a back-up role at this stage in his career. Maybe a trade for Lugo would help at SS.
Chips: Lidge has struggled this season, and I don't think he's untouchable - though I doubt he'd be traded unless it netted a significant part for this team. I think other teams would still have interest in the still-young Lidge. Preston Wilson always seems to be available at this time of year. If the Astros skid after the All-Star break, you will hear whispers about Clemens being available, though he may only be available to the Yankees or Red Sox. The Astros could trade a BP arm in a package deal.
EDIT: Since I wrote this, the Astros have traded for a bat for the OF, Aubrey Huff.
Chicago - Sell
Needs: A new start. It's no longer a matter of 'if' Dusty will get canned, it's just a matter of time. The Cubs need a way to keep Wood and Price healthy and need more help in the rotation. Pierre was a terrible mistake as a leadoff guy and has moneyball GM's, and any GM with a brain, laughing. The Cubs should resist the urge to play veterans when young guys should be getting experience (Murton and Pagel in the OF). Cedeno isn't the answer at SS.
Chips: Veterans should be made available. Maddux has been thrown around as a possibility. Todd Walker is having a solid season and could certainly help a contender with a hole at 2nd. Jones is having a better season than should be expected and they should sell high. Prior and Wood aren't as untouchable as they have been in years past - Prior will cost a fortune and is unlikely to be moved, while Woods shouldn't get much interest with his contract and injury history.
Pittsburgh - Sell
Needs: A solid coaching staff throughout the organization, a better minor league overseer, and attention to investments (young talent). Pittsburgh needs to get some MLB-quality upgrades at Catcher, CF, RF and P. The team needs to build around Jason Bay and stop thinking Jack Wilson is a solid answer at SS. Duke and Perez have shown flashes of brilliance that were inexplicably met with the Pirates suggesting the young pitchers alter their deliveries - both pitchers have struggled ever since.
Chips: Craig Wilson has drawn a lot of interest, and now that Huff (Tampa Bay) has been moved, I expect teams like the Yankees to pursue him a little more aggressively. Casey could be moved, but his average distracts from almost non-existent power. Damaso Marte will draw interest. Kip Wells had team interested in him going into the season, but has been awful this year. Jose Castillo, Freddy Sanchez, and Joe Randa have had decent seasons thus far and could be interesting. The Pirates shouldn't trade Perez, but he's no longer unavailable. It's surprising that a team that has been so bad for so long is unable to establish a solid farm system, but I suppose that reflects on the poor management and lack of interest in the farm that has plagued this franchise for quite some time now.