Great addition. One of the enhancements you can make to your browsers that makes you go "Why wasn't it always like this?".
One significant improvement would be to allow users to reverse order the list. I open a lot of tabs and tended to work from right back to left. In vertical tabs, this means I am working from bottom to top and I would much prefer to work from top to bottom. Please consider allowing users to reverse the order of the list!
