I don't normally do plugs for software in such a blatant manner, but this one fills such a huge gap and is specific to our little corner of the industry, so I thought I could make an exception this time. PPMulator
This was originally a superb 2 channel meter, with variable ballistics and more importantly, variable scales & settings for correctly assessing the peaks & levels in a mix.
With the multichannel world being even more picky, with even more standards, the new implementation really is a "Must Buy" tool.
Best of all, it's only a cheap upgrade if you own the older stereo version.
Please - do yourself a favour & check it out!