I have been playing quite a bit with Ubiquity lately. So far, I think it is really cool. One thing that has always prevented me from really getting into Firefox extension development is the constant restarting. I am a two or three line and test type of developer and that just does not work. But Ubiquity reload all the command every time you open it. And its got jQuery. Since I am living in German now but still earning the US Dollar, I am constantly concerned with the exchange rate and find myself visiting xe.com frequently. Perfect chance to make a new command. So far it just does Euro to USD, I hope to add all their options. Here it is.