Yahoo! has released a beta version of their toolbar for Firefox, if you run Windows.
A Macintosh version should be out soon (you can get an email from Yahoo! when the Mac (or Linux) version is ready by clicking here).
Once it is out for the Mac, I will add it to my Firefox browser (along with my other Firefox extensions, GoogleBar, the unofficial Google Toolbar for Mozilla and my A9 Firefox toolbar). And I can hardly wait for the MSN Search Firefox toolbar for the Macintosh.
Peace – Tim