This free plugin does just one task, generating pink noise. Use it as a test signal for evaluating plugins, as a track level reference, for calibrating your monitors, or gate it off a snare drum (it's automatable, too). A handy companion to MOscillator for test tones.
 
Warning: you are required to give your name and email address, but can opt-out of CredlandAudio's newsletter at the same time. If the name doesn't ring a bell, Jim Credland is best known for his Big Kick kick drum synthesizer and StereoSavage M/S processor and detuner. Both pretty cool but (IMO) a little overpriced at $65 and $79 respectively.

If you have MOscillator, you have MNoiseGenerator too. Not as simple as this CredlandAudio plug-in though.

Link didn't ask me for anything....

scook
If you have MOscillator, you have MNoiseGenerator too. Not as simple as this CredlandAudio plug-in though.

Here's a good how-to video for setting initial levels using pink noise by the always interesting to listen to Andrew Byrne.
 

I can get as good or better mix without the pink noise present by just using my ears.  And the total mix level rms wise being at the chosen reference.  All without that din in your ear.  It is actually an OH&S issue.  
 
One of the issues with pink noise is that it sounds louder than music at the same rms level.  So one could argue that it is in fact a silly concept.  A better approach is using a real VU meter.  With care you can actually get balances rather perfect by just seeing how much more the needle moves as you bring things in.  But it is still only rough guide at best.
 
What is not bad though is having pink noise present down at a low level. That can prevent certain quieter parts from being lost.  Checking your mix in mono though on a small speaker at low volume will also reveal this just as well.
 
I have sat in with some pretty fine mix engineers and none of them did this with the pink noise either. There is no silver bullet for getting a well balanced mix.  It just takes practice and experience. 

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I don't think anyone suggesting this method has ever stated it was a silver bullet.  In fact, most people who mention tend to say it can be a nice jumpstart  but you still have to use your ears.  i have tried this approach out of curiosity and agree.  It's not magical, but for badly tracked initial mixes, it's a decent way to get everything to a good starting point to set initial levels. I appreciate advice from experts but i find sometimes the strong need to bash whatever does not fit their approach a little offputting.  This method DOES have weaknesses but i would not say it was useless as long as you keep in mind it is not an instant "gooderizer". I treated it like a very general preset when i tried.
 

I did not mean the VU meter approach is that good or a better way either.  Some engineers used to use VU meters to start a mix. It is a bit like the pink noise approach.  If something will help you get in the ball park then use it but you will always be resetting in some form after.  
 
I think it was mentioned it is a technique used in EDM music and in that regard it might work well but for other genres of mixing personally I don't feel it is necessarily a great technique.  While some think it may be good on one level I see too many problems with it on so many others.