Worldwide Online Olympiad Training
Worldwide Online Olympiad Training (WOOT) is an olympiad preparation and testing program, run by AoPS, that brings together many of the best students from around the world to learn Olympiad problem solving skills.
The WOOT program includes 16 classes, problem sets, and practice AIME and olympiad-style tests. More details may be found at the WOOT Home Page and Schedule.
All participants from the 2016 Mathematical Olympiad Summer Program program are invited to join WOOT for free, due to sponsorship from Art of Problem Solving and D.E. Shaw.
Other WOOT programs include ChemWOOT and PhysicsWOOT.