I'll point you to this thread which had quite a discussion on monitors:
http://www.thephotoforum.com/forum/showthread.php?t=117716
The summary is a decent monitor for photo work should have at the very least a S-PVA or IPS panel in them. Not the TN panel that gamers use. The TN panel may be crap for colour, but they are the only screens which are capable of the response times good for games.
If you're an avid gamer S-PVA is a lovely compromise. Since going to an IPS panel I have actually gotten motion sickness when playing some games.
Excellent monitors are made by Samsung, Eizo, NEC, HP, and a few other companies. But again Samsung and NEC make some very poor ones too.
Things to look for:
- IPS panel to ensure colours don't shift with viewing angle
- Colour gamut. (wide colour gamut if you know how to use colour management in photoshop or standard if you want to avoid the colour headache and still get excellent photos). By the way the Spyder II does not support wide Gamut monitors despite what it says on the box and I know at least NEC actively say do not use this calibrator with some of their screens.
- Internal Lookup Table. This is the kicker as it will allow proper calibration of the screen. Not the signal that feeds the screen but the screen itself. It will select it's 8bit output from a possible range of 12bit colours according to the LUT which is programmed by the calibrator.
errr that's all I can think of right now.
Dell make some nice S-PVA panels which a lovely compromise.