FireFox is a great open source web browser. If you aren't already using it you should really give it a try.

One of the big benefits of FireFox is it's customizable nature, there are hundreds of addons for firefox. Here are a collection of extensions that are useful for a handmade business.

Etsy Hacks - Collection of Greasemonkey scripts that extends Etsy functions.
Greasemonkey - this extension lets you run a large variety of 3rd party scripts such as Etsy Hacks.
Etsy Search Add Etsy search functionality to your search bar.
Paypal Plugin Use Paypal on sites that don't support paypal by generating a temporary card number.
Blank Canvas Gmail Signatures Automatically inserts HTML signatures into your gmail messages (e.g. linking to your shop)