I think this is a good guide on the topic:
http://www.normankoren.com/printer_calibration.html
Follow the digitaldog link to get some calibration sample pics.
For more on the topic (and more pics) type color calibration on google. Or test patterns
Here's a huge one for fun:
http://www.flickr.com/photos/2125220...56020/sizes/o/
It'd be cool if all printers came with a test pic (jpeg, tiff, whatever) and a calibration chart (a printed chart with what the colors should come out like); idem with monitors.
P.S: Be sure you're using paper recommended for the printer. Something seemingly as trivial as brand of paper can make a difference!