If you were not aware, Firefox 4 was released recently and it’s become pretty popular. According to the download stats, it has been downloaded nearly 50 million times as of this writing. Although admittedly I rely on Chrome to handle the bulk of my work while surfing the web, I have always liked Firefox and do still routinely use it from time to time. One of the main reasons for this is because of all the great add-ons that exist for it.

One great thing about Firefox 4, that I couldn’t say about previous versions of the browser, is that there is now support for restartless add-ons. Not sure what a restartless add-on is? It’s exactly what it sounds like. Restartless add-ons can be installed, uninstalled, disabled, enabled, and upgraded without you having to close all your tabs and restart Firefox.

In this article, I’ll take a look at some of the best restartless add-ons out there so you can start incorporating them into your browsing habits.

1. Mozilla Labs: Lab Kit

The Mozilla Labs Lab Kit is an add-on that automatically checks for new experiments from Mozilla Labs. Included in this pack is F1, which lets you share links from within the browser in a fast and safe way, Find Suggest, which gives you suggestions from the page when finding, Instant Preview, which previews pages as you select them from the location bar, and Speak Words, which allows you to type a single letter in the location bar to go where you want.

2. Mozilla Labs: Home Dash

Home Dash is an add-on that removes the usual location bar, search bar, and tabs to give you access to the whole window to view web content. Don’t worry, you can still get your search functionality by way of the dashboard to find your top sites, tabs, history, and perform web searches.

3. GReader Panel

GReader Panel is key if you rely on your Google Reader feed for information. It pretty much does what you’d expect it to: pop up with all of your feeds for easy viewing. If you aren’t utilizing Google Reader, now is the time to bolster your list with some useful information.

4. Grooveshark Remote Control

As we all know, I’m a devoted Grooveshark user. This remote control add-on is great because it allows you to control your Grooveshark listening from any webpage, rather than having to go back to the tab each time you want to skip to a new song.

5. Tab Badge

Tab Badge adds a small badge to your tabs to alert you whenever, say, you have a new message on Facebook, or a new email. The badge is also visible when tabs are pinned so you can see when there’s something new available. This is the type of functionality I’m used to seeing with the similar lab feature located in Gmail.

Conclusion

Another term for restartless add-ons, which I failed to mention in the introduction, is bootstrapped extensions. These are special extensions that, instead of using overlays to apply their user interface to the application, programmatically insert themselves into the application, thus not requiring a restart. You can learn more about how these types of add-ons work here. Also, be sure to check out our other articles on the subject of Firefox.

Do you have a favorite restartless add-on you’d like to share?