Firefox 3 Rated 5 out of 5 stars
This the one thing I really really miss most about Firefox 3, and I therefore hope, more than anything else about Firefox, that this add-on will be updated, or incorporated into the product.
In the meantime, I thoroughly recommend it to all users of Firefox 2.
It does not take much time being aware of your mouse movements to realise that the icons at the right hand end of a window's title-bar cause you to be moving your mouse more often left to right than right to left.
Not everyone will have the benefit of a flexible desktop environment such as Gnome or similar that allows them to concentrate mouse clicks to the right of the screen, but any tool, such as Sidebar on Right, that helps reduce repetitive strain injury is welcome.