I have been evaluating numerous webmail tools, most of which are free, and quite good. I have tried Iloha mail, and Roundcube, which are both really good freewares. Now, I have come to know v-webmail.
v-webmail is really cool, and ridiculously easy to install. Moreover, it offers a really awesome word processor in the compose window.
This is the webmail to have! Great job!