Pretty awesome idea to create these as firefox-native plugins. Even I as admin will find these to be greatly useful

I think IE7 is also going to allow something like this?

This explanation of how to use Yubnub to search J2O is a good addition, but it's less powerful than your plugins: J2O commands for Yubnub (less features, restricted to Yubnub...)

Here's an addition you can use to allow for quick surfing to J2O sections. This does not in any way replace your plugins, it provides for quick surfing though. I never finished/officially published the page, but might someday.