mzuther has released traKmeter, a free loudness meter for correctly setting up tracking and mixing levels. traKmeter is available for Windows and Linux.
Most digital audio equipment sadly only has peak meters. This is readily understandable as you want to avoid digital clippings by all means. However, the lack of average meters makes correct gain staging almost impossible.
For gain staging, you need average meters or – even better – a combination of peak and average meters. And this is were traKmeter comes in.
traKmeter has an average level meter that is centered around -20 dB FS RMS and a peak level meter that is aligned to -9 dB FS. It supports stereo and 8-channel audio signals, has two scales, two ballistics modes and is very easy to use. Additionally, all meters have been thoroughly validated.
This plugin is available at no cost.
More info: traKmeter