Scrolls the page smoothly when scrolling the mouse wheel (or keyboard arrows if enabled).
AutoPager automatically loads next pages when you reach the end of a page. It works on a ton of sites,Google,Yahoo..
It works well with most other add-ons adblock plus, WOT and most of the greasemonkey scripts.
You can also try AutoPagerLite.
Check4Change (aka C4C) is a simple extension that allows you to select a part of a web-page, and get notified when it changes.
Monitors web pages for updates. Useful for websites that don't provide Atom or RSS feeds.