I vaguely remember having a Firefox plug-in that allow me to send email via Gmail whenever I click on a
mailto: link on any web page. In my search for this plug-in I stumbled across
this site. Nothing spectacular about it until you read about the
Gmail FS.
Now the Gmail FS allows any Linux system to mount the free space on your Gmail account as another filesystem. Now there is a Firefox plug-in called
Gspace that also allows you to use your free Gmail storage but this to me makes more sense since I am using Ubuntu and I do love my console.
I haven't tried it yet, but maybe soon I will give it spin. I still haven't found the Gmail
mailto: plug-in, maybe I dreamed it.