MP3 Diags is a GUI-based application that allows end-users to identify issues with their MP3 files, fix some of the issues and make other changes, like adding track information. It also lets you "look inside" an MP3 file. Unlike some programs that are designed to deal with a single topic (like fixing VBR headers or adding cover art), MP3 Diags is a one stop solution that identifies more than 50 different issues in MP3 files and provides the means to fix many of them (well, not everything is fixable; you can't make a 64kbps file sound like a 256kbps one.)

Linux is the development platform (openSUSE, to be more precise), so the program should work best on Linux. The most important requirement is having Qt 4.3.1 (or above), so I expect most Linux distributions from 2007 or newer to be able to compile and run it (perhaps after some tweaks of the build scripts.)