I'm a photographer so color accuracy is very important to me. For that reason I use the 30" NEC MultiSync PA301W. I have a buddy that works at a high end digital lab in Chicago and this was the monitor he recommended I buy and I have not been disappointed. One of my favorite aspects to the monitor is NEC's AmbiBright technology. There is a sensor located on the monitor that gives it the ability to adjust brightness based on your lighting conditions, which is really nice as the lighting conditions change a lot in my studio given all the natural lighting I have. It works extremely well. Most displays are only able to display 72% of the NTSC color gamut, but the PA301W is able to display 93.3%, a pretty big improvement. If I remember correctly, its also able to display 97% of the Adobe RGB color space.
It definitely cost a bit more than your standard fare, but if your working in the graphics or photography fields, its definitely worth the additional cost. I am currently using it on my old MacPro, but I just placed the order for my new MacPro earlier this evening and there is no reason for me to upgrade or to buy a new one. This monitor is only a year old and still has plenty of life left in it.