Thunderbird extensions: ThreadVis

This is a really, really great extension for Thunderbird. It add a graph to the email view which visualizes the context. This means if you have a conversation over multiple email, it is visualized and you can quickly access the various mail by clicking on the graph. This jumps then for example in your sent folder to you previous mail.
The extension's website is here where you also can download it.

Here you see a screenshot of its visualisation