While working on the white paper about safely and automatically updating the configuration files on a system, we realized that using a web-based update framework might be the way to go. With a powerful Javascript-equipped browser like Firefox and AJAX at your hand, there is not much that cannot be done with a web application. And this strategy works well for updating remote headless servers that are almost always tucked away at some data center.
However, when an administrator has to manually merge the differences between his copy of a configuration file and the one that came with the update, it gets a bit painful. One would have to hop on to the (possibly remote) system, find all such unmerged files and use some local diff/merge utility (hopefully already installed) on the system. It then became apparent that a web-based diff/merge editor might take away some of this pain. It can work stand-alone or within a web-based update framework.
JSBlend is the tool I came up with that can hopefully fill this gap. It is still in its early stages - but in the last couple of releases, it has made some progress in becoming a useful stand-alone tool. (Or so I think!)
It has a small python web server built into it. A single python command can start the server, fire up a browser and let the user edit the desired files. Currently, one of the files is treated as the merge target and other one is read-only. It already handles remote files over SSH, HTTP, and HTTPS.
If this rant has incited some interest in you, take it for a spin. And let me know what features you would like to see in future. Oh, and did I mention it's free - as in beer?