Natural Languange Navigation, a bit more
After showing idea in previous post, there are several more things I would like to explain user scenarios. This interface is made for two things: when user wants to see site he visited, and when user wants to visit new site and is very well aware of what he is looking for (like specific company, institution or product site). In first case (which is more frequent) he uses left column of drop-down. In the second case he uses two other columns.
I think that with this concept, unifying of search bar and location bar is not necessary, as search bar should keep its functionality when user does complex searches and searches for something generic, as whole search engine page is necessary then, and it is easier to get it through search bar. Also, user may want to submit data to different forms and sites, and search bar is handy in that case.