Firefox has proved itself a worthy competitor to Microsoft’s Internet Explorer and Google’s Chrome browsers, but this web browser allows for much more than just surfing the web. Continue reading to see five of the coolest and most useful add-ons. For those who missed our feature yesterday, check out the five coolest Google Chrome extensions here.

1. Video DownloadHelper

Have you ever wanted to save a movie trailer, music video, or even funny spoofs for later viewing on your favorite video sharing sites? Video DownloadHelper makes it a breeze. Simply “surf the web and when DownloadHelper detects it can do something for you, the animated icon menu allows you to download files by simply clicking an item.” Download page.

2. Personas Plus

Spruce up your Firefox browser with Personas Plus. This add-on enables users to choose from over 60,000 themes from 5,000-plus artists. Highlights include: Harry Potter, Lady GaGa, and All American Rejects. That’s not all, you can even rotate themes periodically with Personas Rotator. Download page.

3. Cooliris

Turn Firefox into an interactive 3D wall, with Cooliris. Simply put, it lets you “effortlessly scroll an infinite “3D Wall” of your content from Facebook, Google Images, YouTube, Flickr, and hundreds more.” That’s not all, the official Cooliris Channels feature the latest news, TV shows, and more. Download page.

4. FastestFox

Repetitive tasks be gone! The FastestFox add-on offers users parallelized downloads, word definitions, auto-loading next pages, improved searching, and more. Download page.

5. Greasemonkey

Greasemonkey isn’t the flashiest of add-ons, but it’s most certainly one of the coolest and most useful. It essentially allows “you to customize the way a webpage displays using small bits of JavaScript.” This means the thousands of user-created scripts at Userscripts.org are at your disposal. Download page.