I've built a simple diff front-end for Michel Fortin's great Babelmark. To use it, drag the bookmarklet below to your link bar, then load up Babelmark. Click on the bookmarklet, then click "Compare..." to diff the output from the various implementations. The left column is now grouped by color: implementations that agree on an interpretation of the input are drawn in the same color.
Here's the bookmarklet: Babelmark GUI.
This should work in Michel Fortin's original Babelmark. Since Tomas Doran's mirror of Babelmark now includes an earlier version of this code, the bookmarklet won't work there. We'll get the new version up there soon.
Built with jQuery and diff-match-patch by Neil Fraser (no relation).