I dunno about you guys but i've always hated clicking on the "Contact us" hyperlinks that a lot of webpages have because it ends up loading Microsoft Outlook to send the mail (which I dont use). Well the new firefox/gmail combo can now replace that task so when you click on the 'contact us' links it an send you to the "Compose" page of your Gmail account with the email in question already entered.
http://gmailblog.blogspot.com/2008/07/power-tip-set-gmail-as-your-default.html
I find this super handy since outlook is garbage and a waste of loading time/hardrive space. Thought i'd post it up for others to use to if you find it a pain like I did :P