checkmp3 adds on the oblique ability to “fix” mp3 files, by sending the entire file to STDOUT but omitting frames which appear invalid. I suppose that could technically “fix” an mp3 if you pipe it into another file, but I also suspect it would cause hiccups in some cases. The files I used for a test run were more or less intact, so I didn’t notice any difference in playback.
You see the Debian Squeeze version there (apparently it’s also in Sid), but the man page gives a Sourceforge address which is titled, oddly, MP3 Check. I tried building MP3 Check from scratch in Arch but ran into issues; all the same, I have no reason to believe that checkmp3 and MP3 Check are not the same program. (The mp3check we saw before was strikingly different.)
That’s about all I can think of to say. It’s a very straightforward tool and (apparently) does what it promises. Let’s move on.