What is WebMailCompose? It's a Firefox extension and it can be found here. What does it do?
Tell me how may times you have faced the following situation: You are reading an interesting article and now you want to share it with your friends, so you need to open another browser window (or tab) or go to your already open window (or tab) where you are already logged into your favorite web based mail account. You click on compose, type in the subject, cut-paste the link of the article you were reading and then send it.
With WebMailCompose this will shorten to just File -> Send Link. The WebMailCompose extension will automatically construct the right URL for your web-based mail account and drop you into a new compose screen in a new tab with subject and body of the message filled in. Just type the to: address and click send and you are done. No cut-paste required. Another feature is if you see an email address just highlight it and the right click menu will show you a WebMailCompose option to send a mail to that email address using your favorite web based mail.
All of the following popular web based mails are supported:
gmail, yahoo, hotmail, netscape, mail.com, opera.
If you have your own site hosted with horde or squirrelmail (like I have), that will work too!