A question for the digital photographers out there

As anyone who has done any decent amount of photo editing on their computer knows, getting the colors and brightness just right can be a difficult task.  Speaking for myself, I find it very frustrating to get the image looking good on my main monitor, but when I slide it to one of the others, it loses its appeal. 

 So I’m wondering if any of you have ever used one of those monitor calibration pieces of hardware, such as the Spyder and others like it.  Do they work?  Is it worth it?  Any other recommendations?  I’m using 4 LCDs, no CRTs.

I have tried software based ones (like Adobe Gamma) but often feel that it ends up being sooo subjective that my eyes want to pop out of my head. 

Looking for some advice…