If you care at all about colours and image quality, go for a Dell Ultrasharp. They aren't the fastest monitors around (refresh rates, ghosting), but unless you're very sensitive to this you shouldn't notice. Viewing angles (especially on a monitor as large as 27") are MUCH more important (with a 27" TN panel you might see distorted colours along the edges even if you're looking right at the centre of the display). And did I mention that the colour reproduction of the Ultrasharp series is amazing?
My daily driver is an U2711 - it's a few years old now, but still looks amazing, and works perfectly for both desktop usage and gaming (both PC and Xbox). For me (I'm slightly farsighted) the scaling at 100% is perfect - smaller than "standard" PC scaling (~110 v. 96 DPI), but the screen is lovely and sharp and fits everything due to the size and resolution.
My GF's newer U2713HM is sitting right next to mine on the desk, and is just as good. The anti-reflective coating on hers is slightly less "coarse," so images are a bit sharper. It's also considerably slimmer and takes up less desk space. Colours look slightly less saturated (when both are in the pre-calibrated sRGB mode), but still look amazingly good. I haven't tried gaming on it, but from what I've seen, it might be ever so slightly quicker than mine. And it's cheaper to boot. Of course, if you're serious about photography, you have the more expensive U2713H which has a wider gamut (99% Adobe RGB, 120% CIE1976 and 100% sRGB v. the 99% sRGB and 91% CIE1976 of the HM) and a few extra premium features.
Oh, I just checked the Dell website, and it looks like the U2713HM has been replaced with a model called U2715H. Similar specs, but it looks even nicer, with thinner frames and a more modern design, as well as some additional inputs. Should be just as good, probably better.