This page is incomplete, but should provide a reasonable starting point for those looking to explore bronydom.
The Top 10 Pony Videos
The Top 10 Pony Videos is a long-running project to document and showcase the most popular My Little Pony videos in the brony community. Videos featured on the list are voted upon during a week-long process at the beginning of each month. This project has been active every single month for more than nine years!
The series was originally created in 2011 by The Movie Brony and is currently run by LittleshyFiM, which makes this a sister project of Whatisabrony. It's a great way for newcomers to catch up on the many years of pony videos!
The biggest and longest-running brony blog! As the name implies, you can find daily posts and all sorts of great pony content here. This website was created by Sethisto after being kicked off of 4chan for sharing pony during the earliest history of bronydom.
Founded January 2011 and serving as a central hub for millions of bronies, you're definitely going to want to pay them a visit.
Self-described as a "pony supercommunity," Poniverse is a home for discussion and all sorts of pony media. They also partner with various conventions all in the name of spreading pony.
Each of their websites are well-designed and provide a community to participate in. You can join MLPForums for classic thread-based discussion, Pony.FM for the best brony music, Ponyville Live for internet radio and live shows, and of course the usual social media platforms such as Discord and Twitter.