I liked the project very much, I've been using it today, and despite
some design things that could be better (like the tree display when
there's no sessions history for the current page), I found the
history/sessions form very interesting.
The "top visited" sites page looks very useful, something like the
speed dial or history viewer for Opera, Safari and Chrome.
There's good documentation/help also, which is pretty important for a
project like this.
Thanks for sharing your project,
Nico.