The OU Simple Question, Simple Answer thread is a great place to ask any simple questions you might have relating to the OU metagame. Do not make new threads for questions that could be answered here.
The OU Usage Stats show which Pokemon are used the most in OU on the simulator. The most recent stats are for March 2013.
The OU Viability Ranking thread shows how well every OU-viable Pokémon fares in the OU tier.
The BW2 General Metagame Discussion thread is an open platform to discuss any aspects of the current BW2 OU metagame.
The Unofficial Glossary offers useful definitions for common competitive Pokemon terms.
The Creative/Underrated Sets project showcases and promotes new and creative sets that are still highly effective.
The Don't Use That, Use This project aims to help new players by creating a list of what not to use and what to use instead.
The Gimmicks and Their Role in the OU Metagame project provides a platform for members to showcase gimmicky and creative sets.
Looking Ahead to Gen VI features a different new aspect of Generation 6 each week for competitive discussion and speculation.
Lower Tier Threats is a project that aims to compile a list of notable lower tier threats through poster submissions.
The OU Community Create-A-Team project aims to build an effective team for the OU metagame through community submissions and voting.
The OU Teambuilding Competition gives a two Pokemon core for members to build the best possible teams in order to win in a community vote.
The OU Team Study presents a team with some questions about it, requiring posters to think critically about their moves.
Research Week takes a group of two to three Pokemon every couple weeks and challenges users to pick one and ladder with it, as well as share their insight on their chosen Pokemon based on their experiences with it.
The Teambuilding for OU project takes user submissions in order to compile lists of Pokemon that can fill various roles.
The Next Big Thing takes a look at a different Pokemon each week in an attempt to find new and creative sets for it.
Theorymon Session and Viability Ranking is a project that enables members to ask "what if" a certain Pokemon got a particular ability or move, 10 of which are implemented on Pokemon Showdown each month.
Victim of the Week features a different Pokemon each week with the intent of finding the best counters and counter-strategies for it.