I noticed that the mozilla site recognizes microb as firefox 3.5.
Also any firefox add-on can be installed in microb and accessed for configuration.
However none of what I've tested so far seem to work:
Video capturing:
https://addons.mozilla.org/en-US/firefox/addon/2254
https://addons.mozilla.org/en-US/firefox/addon/3006

Or a very neat plug-in that will help you never miss a click:
https://addons.mozilla.org/de/mobile/addon/50422

So what makes them tick?
Do they need to be recompiled for ARM?
Do they need special compatibility fixes for microb?