Joe Janish beat me to it. Check out Mets Today for a complete rundown of the call-ups and who can and can't be added.
I'm not going to put a lot of stock into Jon Niese or Bobby Parnell. There seems to be too much hype behind them, and I don't think they're going to come up and have a huge impact on the team.
Guys like Al Reyes and Ricardo Rincon should help, simply because another arm in the bullpen cannot hurt at this time. It's a crap shoot in the pen right now, and Luis Ayala worked for a few games. Lightning in a bottle could be found anywhere. Hopefully one of these guys can be a lightning rod.
Marlon Anderson will be nice to have back, as long as he can recapture his pinch hitting prowess.
Don't look for a huge help from the September call-ups, but Niese will get the start on Tuesday against the Brewers. Maybe he could do something special against the streaking Brew-crew. Wouldn't that be nice?