I have used the colorvision, Display Eye One, and now I am using the Macbeth Spectrophotometer.
I originally got the colorvision spyder, because it was cheap, and a few people on the HT forum was using them to calibrate HDTVs. but soon enough I figured that its very limited for what I do (your mileage will vary).
At the time, and probably still is, Macbeth is in the color industry. So I opt for the higher priced Display Eye One, ended up being the same damn thing as the Colorvisoin Spyder. the only difference I saw as the the Macbeth maybe about 100 Kelvin more accurate.
So comes what I have now. the Eye-One Pro spectrophotometer. Which is so powerful it's scary. Paired up with ProfileMaker v5+, it is unbelieveable powerful (after spending 3.5k)
Like I said earlier, it depends what you need it for. For most home photographer not going "pro" getting your monitor calibrated is good enough. But if you have gallerys and pre-press printing, you got to have the full package.

