World Schools Debating Championships: The World Schools Debating Championships (WSDC) is a high profile annual English-language debating tournament for high school-level teams representing different countries.
[Info][Official Site]

Academic Competitions: Inside
[ Math Competitions ] [ Science Competitions ] [ Spelling Bees ] [ Music Competitions ] [ Robotics Competitions ]
[ Debating Competitions ] [ Programming Contests ] [ Quizbowl ] [ Olympiads ] [ Various ]

Various Includes: Academic Decathalons, History Competitions, Geography Bees, Internet Competitions