There is a very nice Javascript Console available at http://www.squarefree.com/shell/shell.html; I've ported it into XBLinJS to replace the hacky little one I had written. I've tweaked it up a bit and also removed a little bit of functionality; in particular you can't start up the Console from a bookmarklet in the context of the original page, and it is easier to create subclasses with customized shell commands and keyboard shortcuts.

This is in CVS, though I have not tested it in IE, which typically means it won't work there yet.

This is an example of XBLinJS's capability to unify the many disparate little chunks of Javascript functionality out there in the wild into one coherent library format; now it's all nicely wrapped up and easily added to anything. I haven't talked about this much because I've had nothing to point at, but I've got a couple of other widgets like this lined up, ported from other sources but wrapped up so anyone can use them just like any other XBLinJS widget, not on a per-library basis. (This widget did not gain much from the conversion, mostly getting off of using global variables, but one of the other widgets I've preparing, a Rich Text Editor, is benefitting greatly from XBLinJS, both simplifying some of the code and actually gaining customizability at the same time.)