The great guys at Mozilla have released an early alpha release of a extension for Firefox called Ubiquity. In short, this is where the web is going, allowing you to use everything on the web together. I could try to explain it but I believe the video tells it all:
UPDATE: I just found out that Ubiquity was created by the guys who made Enso, that’s why it looks so similar!
If you’re interested in trying out Ubiquity 0.1 Alpha (keep in mind that it still has lots of bugs and isn’t really user friendly yet) you can install it here.
Once you install Ubiquity, you might want to download new commands, to find those, you can go here.