Adblock Plus

This one does pretty much what it says on the box: Adblock blocks ads, and does so with grace and aplomb. This is one of the universals that pretty much every Firefox user I know has installed, and is one of the hardest to live without. Also updated for Firefox 3 is the Adblock Filterset.G Updater add-on companion for Adblock.
该扩展可以过滤网页中的广告元素，既净化了页面又可以缩减页面下载时间。同样你可以使用 Adblock 来下载 SWF 格式的 Flash。

Download Statusbar

While the Firefox 3 download manager has been revamped, some folks have slightly more hardcore download requirements, which is where Download Statusbar comes in. Freshly updated for Firefox 3, this is one of the more popular Firefox add-ons out there.
一款增强型的 Firefox 下载管理组件，提供增强型与迷你型两种界面.个人认为，采用 All-in-One Sidebar 将原有下载管理器添加到侧边栏也可以达到类似的易用度。

Faviconize Tab

This is the one add-on I really have a hard time living without, and I’m unbelievably happy it’s finally updated for Firefox 3. I danced a dance of joy when I was finally able to stop overriding my add-ons compatibility check (which is generally a terrible idea) and could actually install Faviconize Tab for real. Such a simple thing, but such an incredibly useful thing. I love this add-on.
使用该扩展可以隐藏页面标签上的标题文字，仅留下网站图标（Favicon），通过自定义规则可以对某域名下的所有页面进行设置。个人认为，宽屏条件下其优越性不明显，同域名下的多标签容易产生混淆。此外如果认为默认的标签宽度过宽可以使用 Tab Mix Plus 进行设置。

Firefox Companion for Ebay

- I’m still a little afraid of Ebay (impulse shopping habits + credit card + 24hr access to a world of awesome things to buy = fear), but I do use the Companion to watch some of the more interesting auctions I run across.
本人更接近的服务商是淘宝，未曾使用过 Ebay，不做评论。

Flashblock

One of the more infuriating things about trying to read on the Web are the flippy flashy animated doodads that hover around the margins making it impossible to focus. This is pretty much what Flashblock is created to fix, blocking the animated fiddlybits until you click a button on each to display it. This is a vital sanity saver for me, and I’m really glad it’s updated now.
用来屏蔽网页上的 Flash 和 Shockwave 内容，让用户可以有选择性的查看。

FlashGot

If you do a lot of downloading, FlashGot is a must-have Firefox add-on. This being updated for Firefox 3 is going to save me a ton of time and mouseclicks.
使用该扩展可以在 Firefox 中调用本地的各种下载工具，例如迅雷、快车、Bitcomet等。当然，迅雷用户也可以使用迅雷自己提供的 Firefox 扩展。

Forecastfox

Being Canadian and currently on the edge of summer, I’m a little obsessed with the weather these days. When it’s not raining, or cold, or too windy to stand up, or dark, it’s actually gorgeous out, and keeping close track of when that sun is going to shine is a vital part of day-to-day life in May. Forecastfox being ready for Firefox 3 means I don’t have to obsessive-compulsively reload the Environment Canada website any more.
天气预报扩展，对于国内用户而言其优越性也许比不上 QQ 或者各种桌面工具。

GooglePreview

This is actually a “new to me” add-on that I discovered yesterday, but it’s really great. Again, it’s simple and unobtrusive, just quietly enhancing your Web experience without getting in your way. What it does is add a small preview thumbnail to your Google search results. It’s just neat.
激活该扩展后，会在 Google 搜索结果的条目前显示当前的页面预览图。至于页面载入速度……

Live HTTP Headers

This one’s for the Web Developers in the audience, as it lets you view the running stream of HTTP headers of the pages you browse. Very useful, and ready for Firefox 3.
适用于开发者捕捉 HTTP 头信息，类似 IE+HTTPWatch 的组合模式。对于一般用户而言非必备。

Mouse Gestures

This is another “new to me” add-on that I was playing with yesterday that may change how I use the Web. I never really thought much about mouse gestures until I started using them, and it turns out they’re actually pretty awesome. I’ll definitely be messing around with this one for a while to see if the novelty wears off, or whether it’ll be a long-term sort of add-on for me.
使用该扩展可以自定义各种鼠标手势以实现类似或者超越 Opera 的各种操作。此类扩展很多，但是目前支持 Firefox 的甚少。

Noscrīpt

Noscrīpt is a hugely popular security-related add-on that gives Firefox users very fine-grained control over what Javascrīpt, Java, and executable content is allowed to run in the browser.
拒绝运行页面脚本的扩展，以获得更高的安全性当然会损失页面设计者提供的某些功能。

ScribeFire

Formerly known as “Performancing”, ScribeFire is a very cool and full-featured blog editor that integrates with Firefox. Now that it’s ready for Firefox 3 I’m going to start using it again — it makes sense to have a blog editor integrated with a browser, in my opinion, because blogging is so absolutely tied to the Web. ScribeFire has come a long way since its original launch, so if you haven’t checked it out lately, you should take it for a spin.
Firefox “平台”下的博客离线书些工具。打开浏览器进行离线书写——与原始的发布方式比较其意义巨大么？对于 Bodhi 而言，Windows Live Writer 是最佳的选择。

Shareaholic

If you’re like me and spend a whole lot of time looking at things on the Web, you end up finding piles of things that you want to share with other folks. Shareaholic is a fantastic add-on for this, integrating with digg, del.icio.us, facebook, foxiewire, friendfeed, google bookmarks, google reader, magnolia, reddit, stumbleupon, tumbler, twitter, and more. Jay Meattle, the developer who also happened to win the Extend Firefox 2 contest with this add-on, has recently updated it to work with Firefox 3. And there has been much rejoicing.
不错的信息分享工具，但是对于国内用户而言某些服务台太陌生了。

Speed Dial

The Speed Dial feature was originally debuted by the Opera web browser, but several add-ons mimicking the functionality very quickly came available for Firefox. I like Speed Dial in particular because it’s very straightforward, super easy to customize, and is now completely up to date for Firefox 3.
使用该扩展可以实现类似 Opera 的 Speed Dial 功能。如果你喜欢，那么这是个好东东。

StumbleUpon

I didn’t actually start using this add-on until my Dad told me about it one day, and now I’m a bit of an addict. Be wary, however — StumbleUpon is a bit dangerous in that it can eat days of your life if you’re not careful. I’m just glad the toolbar can be toggled on and off, else I’d never get anything done. Fun stuff, extraordinarily popular, very slick.
StumbleUpon.com 的工具条扩展。具有类似 Digg 的评价机制，也可以向用户推送相关话题的高质量页面。Young 对此扩展做了详尽的描述。个人使用感受是……当心被撑到 ^_^

ThumbStrips

ThumbStrips creates a browseable graphical timeline of your surfing history that is displayed along the bottom of the browser. Originally I figured it would be like another, fancier version of tabs but it’s not that at all — it makes flipping back and forth through your recent browser history really easy, which can be great in situations when you’re checking out Google search results and so forth. Neat stuff.
用缩略图的方式记录并显示你的浏览历史，比原始的浏览历史列表更为直观。如果你希望自己的浏览器主要精力用在页面渲染和处理上，那么就华丽的飘过吧。

TwitterFox

Being slightly unnerved by social networking in general (FaceBook, LinkedIn, etc.) I generally don’t spend much time on such sites, but I’ve made an exception for Twitter. Twitter is simple and fun. It’s also useful, believe it or not, and (if you keep your “Following” list pared down sensibly) it can be super interesting and informative. TwitterFox is a neat little add-on that integrates Twitter right into Firefox that works well and generally does what you expect it to do.
Firefox “平台”下最为优秀的 Twitter 客户端。

Video DownloadHelper

If you’re interested in saving Web videos to your local machine — for example, to watch while on a plane or otherwise offline — Video DownloadHelper is a great add-on to use. Sites it works with include YouTube, MySpace, Google videos, DailyMotion, iFilm, and others.
视频网站一般将 SWF 格式的播放器嵌网页中，并用其播放服务器上的 FLV 视频。使用该扩展你可以轻松获得 FLV 文件的物理地址并下载之。

Web Developer Toolbar

Chris Pederick’s Web Developer Toolbar is one of the absolute must-have Firefox add-ons if you’re a Web Developer. It’s been around for years and puts a world of useful utilities at your fingertips, saving time, effort, and frustration.
一款为网页设计者提供的优秀的、强大的、美观的调试工具。之前有人宣称“即使不懂 CSS 也可以设计出美观的页面”–我说这是异想天开呢。生产者和生产工具的辩证关系应该在初中时便很明晰了。

Wizz RSS Reader

If you’re a bit of a Webfeed junkie and LiveBookmarks aren’t enough, you’ll probably want to check out the Wizz RSS news reader add-on. By way of the sidebar, Wizz lets you subscribe to Webfeeds and quickly flip through new posts or updates to those sites. Wizz is, in my opinion, a great middle ground between LiveBookmarks and a full-featured desktop Webfeed client like Vienna.
RSS 订阅工具，其功能与主流 RSS 工具没有太大区别。我一直不太明白介于在线工具与离线工具之间的定位有何优越——例如上面提及的 ScribeFire。