It totally changed my internet browsing experience! I don't need to search where was that tab. I know where I got there from (on which page I clicked a link when new tab was opened). I know which crappy site opened a new tab without my permission. I can close whole "topic" of tabs. It is like the already existing tab-groups but evolved onto a higher level and on steroids. Problems? There are some: firefox memory limits and the fact that my browser often has 1k+ tabs opened at a time. Over a thousand - and it still works :D Don't try this on chrome or safari. Not even mentioning IE. TreeStyleTab is just great. And user experience is nice as well (Piro provided links on how to deal with UI restrictions - could be more permanent/readable but it is there.... to solve issues that he couldn't do on his own).