A massive data leak was recently discovered by cybersecurity researcher Sam Jidali, revealing private information for 45 major companies and millions of individuals.

If you feel nostalgic for the way YouTube used to be, or at least how it used to look, it’s possible to go back. An extension called “YouTube Classic” for Firefox and Chrome allows you to de-age the web video hub with a retro skin that reverts the site to how it looked once upon a time.

If your Firefox browser add-ons have suddenly stopped working, are now “unsupported” without any warning, or you can’t install any new ones, don’t worry: Mozilla is aware of these bugs and is working on fixing the issue. Resist the urge to adopt any clever workarounds right now, which might mess up any solutions Mozilla is trying to implement.

Chrome and Firefox: Pop-ups are back, baby! They offer 10% off, they ask you to subscribe to newsletters (sorry), they pull up a chat window so customer service can help you spend your money. If those chat pop-ups freak you out, try blocking them with the Hello, Goodbye extension.

Firefox: Snoozing emails is a pretty common practice these days, so it makes sense to bring that same feature to your browser. Chrome has the Tab Snooze extension, and Firefox users can get it using Firefox's own Test Pilot extension.

Most services you might use to save links for future reference or reading are part social network and part sharing service. They're designed to help you share those links, or make big lists. LinkLocker is none of those -- it's completely private, and the only person who can see your bookmarks is you. It's perfect.

Chrome/Firefox/Opera: When Privacy Badger launched a few years ago, it was already a great tool to block third-party trackers, speed up the web and stop sites from watching your every move while you browse. The latest version is a huge improvement, in almost every way.

According to a report from the German television channel NDR, Web of Trust, one of the top privacy and security extensions out there, collects and sells a bunch of data about your browsing habits and doesn't anonymise it properly. If you have it installed, it's best to uninstall it right now.

Firefox: We were fans of MailTrack when it was a Chrome extension because it's one of the simplest ways to get read receipts for emails you send on Gmail. Now, it's available for Firefox too.

You know you're supposed to use a password manager. In fact, you've been meaning to set one up for a long time, but haven't taken the plunge yet. Even popular ones, like LastPass, seem like a pain to set up. Good news: Getting started with a password manager is easier than you think.

Chrome/Firefox: Last week, we showed you how to access Netflix's secret codes pages that direct you to specific movie categories like film noir, satires, or slapstick comedies. Super Browse is an extension that integrates that directly into the Netflix site.

LastPass is one of the best password managers around. Today it gets a bit better with an improved interface and a handful of new features.

Chrome/Firefox: Hotspot Shield, a VPN we've highlighted before, just unveiled a pair of proxy browser extensions, complete with the option to set your own virtual location. That makes it perfect for bypassing pesky location restrictions on streaming movies, music, and web pages.

Chrome/Firefox: YouTube doesn't run very efficiently in Chrome and Firefox. In fact, How-To Geek points out, it's a battery hog. You can get around this problem with the h264ify extensions.

Windows/Mac/Linux: Previously mentioned Firefox extension and Internet Explorer plugin LastPass has updated, adding an automatic form filler to help you save more time filling out forms on the web. We've been on a bit of a password syncing kick lately, what with Foxmarks adding support for password syncing and our own guide to syncing passwords with Dropbox, but LastPass' seamless browser integration for syncing both passwords and forms could attract a lot of people. After all, these useful features earned LastPass its honorable mention in our Hive Five Best Password Managers less than a week after we covered it. LastPass is a free download, works anywhere Firefox and IE do. LastPass

On the heels of Better Gmail 2, the Better GReader Firefox extension is now fully compatible with Firefox 3. The latest compilation of the best Greasemonkey scripts for Reader got an update to the nifty Preview Item inside Reader feature, too. Download it here.

Now that Mozilla's locked down Firefox 3's feature set, it's clear the new browser iteration will render some extensions obsolete. Firefox 3 will include functionality out-of-the-box that you could only get with add-ons before. Let's take a look at five extensions you might not need when you switch to Firefox 3.

Firefox with Greasemonkey: The Google Inline MP3 Player Greasemonkey script inserts Google Reader's MP3 Flash player next to any linked MP3 file you stumble onto while browsing. Simply click the link the script inserts next to the linked MP3 to toggle the player and start streaming the file. For example, once you install the script and reload this page, the Google Inline MP3 Player script should automatically insert a toggle link behind this link. Click it to listen to the MP3, and when you're done, click the Hide Player link to remove the player and return to your regularly scheduled browsing. Google Inline MP3 Player is an update to my original version, works anywhere you've installed Firefox and Greasemonkey. To install, just click the link below.

Google Inline MP3 Player (Click to Install)

Firefox with Greasemonkey: The Gmail Addons Greasemonkey script embeds any page you specify inside Gmail's interface. By default, it comes with Google Calendar and the Google Talk gadget. (If this sounds familiar, it is—Gmail Addons is an update to the previously mentioned Enhance Gmail script.) Add any other web pages to Gmail by following the directions on the script homepage. If you're willing to dig into manually editing the script, Gmail Addons can embed Google Reader, Notebook, Docs, Remember the Milk, or virtually any other web page you'd like next to or below your inbox. Gmail Addons is free, requires the Greasemonkey extension to run.

Gmail Addons