Ben Fry has developed this very nifty graphic showing the relationship between the payroll and team success throughout the Major Baseball league. Check out the graph at his site, which will show the changes throughout the season, but here's a quick explanation of that the lines mean:
A steep blue line means that the team is doing well for its money, which reflects well on the team's General Manager. A steep red line implies that the team is throwing away money. The thickness of the line is proportional to the team's salary relative to the others.
Naturally, the Yankees' line is like it was made with a fat red Crayon. By the looks of it, the Mets are doing pretty well (an expensive team, but, hey, they are working), but the Colorado Rockies have a pretty good record for the third lowest payroll. Although other sports leagues have salary caps, we'd be curious how this looks for basketball, given the Knicks' recent pitiful season and huge payroll.
You can see how the graph works by looking at the graph for the 2005 season.