Check out the ASUS PB278Q. $549.00 on Amazon right now, 27", 2560x1440, 16:9 ratio. I upgraded from a HP LP2475w (24", 1920x1200) and it is a night and day difference.
I now have two of the ASUS monitors (one at home and one at work) and could not be happier. I run them on a $6 Monoprice Mini DisplayPort->DisplayPort off a Retina MBP.
Unless you need 16:10 for some reason, the ASUS are the best deal around right now.
I picked myself up an Auria EQ276W earlier this year and couldn't be happier. It is a 27" 2560x1440 IPS (16:9), same as the Asus, but it can be found for $399. I did replaced the stock stand with an HP branded Ergotron LX stand ($80) as the stock stand only had tilt control, though.
I got an Auria, and I think I got a dud based on what my friends say. :( I can see colors shifting on the screen even when clicking different "inbox" tabs inside of Gmail. The text isn't very sharp, it's fuzzy. At first I thought it was because of the AD coating...but now not sure. I'm going to go talk to the place I bought it from, hoping they'll exchange it or something (even though it's been a few months since I purchased).
I now have two of the ASUS monitors (one at home and one at work) and could not be happier. I run them on a $6 Monoprice Mini DisplayPort->DisplayPort off a Retina MBP.
Unless you need 16:10 for some reason, the ASUS are the best deal around right now.