VU Meter???

If you're looking for a reliable set of VU meters give these a try.  They're about $15 US.
 
http://klanghelm.com/cont../products/VUMT/VUMT.php

There are VU meters offered by PSPaudioware.com
 
I use  the PSP TripleMeter
 
http://www.pspaudioware.c...eters/psp_triplemeter/
 
Check out the video  PSP TripleMeter Video
 

It is one way of maintaining correct rms gain staging right throughout the production process.  The VU meter is setup so 0 dB VU aligns itself to a digital reference below 0 DBFS such as -14, -18 or -20.  Then you can track onto your tracks with the VU just hitting 0 dB VU on the way in.  It ensures all your tracks are recorded at the same rms level.  It also helps you set the recording level which is something many have problems with. It makes it all easy.
 
VU's can be put over buses and the main mix as well to ensure the same ref level is maintained in both of those places.  With the headroom built in you dont have to sweat peaks so much.  They won’t move the VU much anyway and the headroom will ensure they are not clipped pretty well anywhere.
 
It is a handy tool for checking rms levels in and out of plug-ins and plug-in chains as well.
 
VU's should be used in conjunction with peak metering because the very fast transient sounds will slip past the VU meter and you need your peak meters to keep an eye on those types of sounds. eg drum sounds.  But apart from drums nearly all other types of signals can be monitored very nicely rms wise.
 
It is older concept that was all we had years ago and it seemed to work.  Modern DAW's made the mistake of cutting them out but now they have made a comeback.
 
Although DAW's such as Sonar and many others do offer rms indicators they are way too low on the scale to be very useful.  The VU is making use of the full scale deflection making it much easier to see.
 
Real VU meters offer more information in the ballistics of the meter.  eg how it dances to the music.  When a real VU swings wildly it means something is out of control and often you can track it down and sort it out. The virtual meters are not quite as good as an expensive quality VU movement ballistics wise yet but some of them are getting better all the time such as the Klanghelm meter for example.
 
Maintaining the same peak levels on your tracks mean the rms levels are all over the place that live under the peak values.  Keeping rms levels the same and letting the peak levels vary make it much easier to mix. Because all your tracks will be at the same volume level.  Something that does NOT happen when you maintain incoming peak levels to the same value.  Ever had a track that is too soft to be heard in a mix? Reason is that the rms level is too low.
 
They are just nice to look at too!
 

Thanks for all the info Jeff. Gave tnipe's idea a vote over in the bakery. Though I suspect I'd need a tutorial to figure it out if Cake decides to add it ever!

Please refer to the where you got the quote from. At first you said they were only accurate at one frequency which is obviously completely wrong.
 
The VU meter is designed to read voltage in the analog world, not current. (Let me clarify here. Yes a very long time ago it was showing power transfer over a 600 ohm telephone line but since then the impedances that exist in audio signals being transferred from point A to point B are much higher now hence the fact that it reads voltage these days not current)
 
In the digital world it shows very well what the average or rms level of the signal is making it a fabulous and seriously tool.
 
Please click on this link, unzip and read the following attached article. You might learn something about them and even change your mind.
 
https://drive.google.com/file/d/0B_2Jb7O_b5BkeVB3dFVsUm8zelE/view?usp=sharing