Look for a S-IPS display LCD since most LCD's are of the cheaper TN (twisted nematic) displays if you can afford it.
One of the HP models and most of the Apple Cinema's have S-IPS technology. It's a good deal cheaper but the color reproduction, accuracy, and viewing angle is superior to all the other LCD technologies.
Apple 20" Cinemas run about 800 the HP LP247BW 24" display on Amazon runs about $610 (hence if you can afford it). The S-IPS is about 2-3x in cost to a reasonable TN of similar build quality.
I have a Samsung TN type display right now and I'm miserable trying to edit photos such that what I see is really what will be reproduced. If you can afford it and you really do a lot of photo editing + proofing, I would invest in a S-IPS LCD display.