I mix at home with headphones.  Unfortunately it's my only option outside from sending the tracks to a studio to actually mix in a GOOD room...
 
I'm thinking about buying Waves NX - Virtual Mix Room, but the only reviews I can find online are basically sales-pitches.
 
Does anyone have any opinions on it?  Waves is selling it for $49, and I'd be happy to pay that if I thought it would help my mix.
 
http://www.waves.com/plugins/nx#introducing-nx-virtual-mix-room
 

What Nx is a more of a "Stereo Field" plugin...

If you mix with Headphones, then you need to get
Sonarworks Headphone Calibration Plugin and, if
you don't have a pair of cans that are on their calibration
list, then get a pair....

THIS will help you mix far more then Nx will...

+1 to what Larry said.
 
As for reviews, there are many on YouTube (not made by Waves). Here's one, for example:
 
https://www.youtube.com/watch?v=SBFZ3GquYR8
 

You should be able to get it cheaper than that at everyplugin.com. Even cheaper with latest code, which I don't know. Anybody... anybody.. Bueller?

Ferris has left the building.

Sonarworks refererence 3 is what you want ....

Zo
Sonarworks refererence 3 is what you want ....

I likes it.
 
http://forum.cakewalk.com/Just-got-Waves-Nx-to-try-it-is-interesting-Updated-with-Headtracker-opinions-m3480353.aspx
 
I find it compares favourably with my surround sound setup. It isn't going to replace it, but it is impressive what a good job it does when paired with its head tracker.

Great, thanks everyone!

So 2 weeks later...
I pre-spent my Christmas bonus.  
Waves NX:  Seems pretty good at resolving the panning issues that come with using headphones (the isolated ears).
Beyerdynamic 990 Pro Headphones:  I needed (wanted) new headphones, these had decent reviews and I found a realtively inexpensive pair.  They sound and feel great.  Plus, they're on Sonarworks' list of pre-calibrated models.
Sonarworks Headphone Calibration:  This seemed to have a minimal benefit, but for the cost I'm glad to have it.  
Between those 2 applications, my mixes are sounding more reliable when played on other sources.  I think they're both worth having, and they cover completely different aspects of the mix well.
 
Thanks for your help guys!