I've found this to be a useful tool.
I use it to compare different versions of the same cd (especially some of the HDTracks releases to original CD). I'm sure this goes without saying but I've found that the version with the highest dynamic range will invariably sound the best. Listening alone will tell you this I know, but this gives a reason for the difference in sound quality.
I use J River as my audio player but have foobar installed as well.
Once the plugin is installed, I just load the files into foobar, select them all, right click on them, then click on Dynamic Range Meter from drop down list. The files are automatically processed in just a few seconds. To see more detailed results, the results are automatically copied to your clipboard. I open Notepad and hit paste, which gives full results for each song.
I'm no expert so I would be interested to hear what others think of this.
I see on the web site posted above that this version expires Aug 31 2011, but there will be a new version released.