Like Firefox has add-ons, Chrome browser has its Add-on: Chrome Extensions:
What are extensions?
Extensions are extra features and functionality that you can easily add to Google Chrome. By using extensions, you can customize Google Chrome with features you like, while keeping your browser free of things that you don’t use.
There are two resource for Chrome extensions: one from Official Google, others from 3rd party companies or persons.
Here is Official extensions list: Official extensions for Google products
Here is from 3rd parties: Google Chrome Extensions Gallery
Most popular extensions: Most popular