This extension can simplify the rule to just specify the URI and Content type and can enable/disable each rule separately.
What's more, it can customize the web pages by user scripts which is similar to Grease Monkey.
Extension to add desktop notifications into firefox, the way it works with Chrome and Chromium Browser : works with gmail, gtalk (gmail chat), imo.im, and all other websites that use this technology.
Customize Your Web (CYW) let's you customize your favorite websites with just a few clicks. What Greasemonkey is for developers is CYW for non-developers. You can remove/rearrange /modify elements, add keyboard shortcuts and do many other things.
Record, bookmark and replay your browser activities in a snap with DéjàClick. Designed for Firefox, DéjàClick can handle the most complex websites - including AJAX, Flash, forms and more. With a single click you can repeat your most common tasks.