Here is something very useful that i found on another site.
With all this talk of the Web as a platform, it's worth taking a closer look at what web apps are using Firefox as their platform. Firefox is regarded as the best Web browser in terms of extensions - i.e. small browser add-ons which modify or add to existing functionality. It has hundreds of add-ons, which can be downloaded from here. But which are the best 'web 2.0' add-ons for Firefox? And I'm using the term 'web 2.0' very broadly here, to mean any add-on that has a social Web aspect to it.
Based on Mozilla's list of recommended extensions, AdaptiveBlue's Alex Iskold and I have generated a top 10 list of Firefox Web 2.0 add-ons. As always, let us know your own favorite add-ons in the comments.
Smart Browsing / Personal Productivity
Browster
Browster is a very cool add-on that enhances your browsing experience - for example mousing over a link gives you a preview of the website. It enables you to speed up your browsing experience and can save a lot of clicks in the long run. It does this by automatically pre-fetching links. It's a free add-on for both IE and Firefox - and hopes to make a profit by putting ads in the pop-up previews.
Answers
Answers is an add-on that promises to "instantly deliver the information you are looking for". It comes from answers.com, which is a popular online dictionary and Wikipedia syndication site. Alex says this is a "perfect example of smart integration with a service in the browser". The Answers add-on works like this:
"Just point at any word, hold the Alt key and click. Upon letting go, an AnswerTip in the form of a pop-up "information bubble" appears on the screen explaining the term."
blueorganizer
The blueorganizer smart browsing extension for Firefox is developed by Alex's company adaptiveblue. This extension drives productivity by building smarts and semantics into the browser. The blueorganizer integrates with many popular sites and services - including Amazon, Flickr, YouTube, iTunes, Odeo and Netflix. It utilizes Amazon's S3 storage service, as well as being run from the Firefox browser - so it is using the Web as a platform in many ways. SolutionWatch has a great review of blueorganizer, if you want to find out more.
Bookmarking / Social Bookmarking
delicious
The del.icio.us extension for Firefox allows you to easily bookmark webpages in del.icio.us, from within the Firefox browser. It integrates with the Firefox toolbar and provides extra options such as right-click menu and highlight text to add notes.
StumbleUpon
StumbleUpon is an increasingly popular bookmarking tool - indeed in my recent post about the Turkey market, we discovered that StumbleUpon is a very popular app in Turkey. The StumbleUpon add-on is described as "collaborative surfing tool", because you can browse websites according to what other people recommend.
ClipMarks
ClipMarks is an early pioneer in the clipping space. Users clip pieces out of web pages and share these bits with each other. They can also tag and lookup the clips, but not much more can be done since the information is not structured. The Clipmarks Firefox add-on integrates this with the browser.
Google Notebook
Google Notebook is very similar to Clipmarks, but has better Firefox integration. It also works in IE6. As with Clipmarks, the user manually extracts text and images out of the page - but this information is unstructured. Google Notebook has had mixed reviews so far, but we think Google is currently putting in resources to improve it.
Foxmarks Bookmark Synchronizer
FoxMarks Bookmark Synchronizer is an easy way to sync your Firefox bookmarks, if you use Firefox on more than one computer. It is very simple, but does its job nicely and has been well received by Firefox users.
RSS Readers
Unfortunately, we are not aware of a really great RSS Reader for Firefox. If you know of one, please mention it in the comments section. In our opinion the best reader in a Mozilla-based browser is the one which comes with Flock. It would be great if someone got inspired, extracted it and released it for Firefox - since Flock is also open source.
There are however two RSS readers that most Firefox users rely on:
Sage
Sage is a basic and lightweight RSS Reader, although you need to be a techie to use it. It leverages Firefox bookmarks to store feeds - and it does the job pretty well.
Wizz RSS News Reader
Wizz RSS is a fancier reader that works well. It supports OPML import and export, plus has advanced features like filtering news items on words and/or phrases. But it is still not as smooth in terms of usability and options as the Reader that is built into Flock.
Conclusion
Firefox is currently one of the best platforms for building a new breed of web applications, on top of the emerging Web Platform. Given its native support for JavaScript and excellent extension API, we expect to see more complex and more tightly integrated web apps built on Firefox in the near future.