As I understand it TTM stands for (Trailing Twelve Months) which I think to mean the standings over the last 12 months.

Top 10 Wii Games
August 2011

  1. Just Dance Summer Party
  2. Just Dance 2
  3. Mario Super Sluggers
  4. Zumba Fitness
  5. Phineas and Ferb: Across the Second Dimension
  6. New Super Mario Bros. Wii
  7. The Legend of Zelda: Twilight Princess
  8. Mario Kart Wii
  9. The Smurfs Dance Party
  10. Cars 2: The Video Game

Top 10 3DS Games
August 2011

  1. The Legend of Zelda: Ocarina of Time 3D
  2. Resident Evil: The Mercenaries 3D
  3. SUPER STREET FIGHTER IV 3D EDITION
  4. Shin Megami Tensei: Devil Survivor Overclocked
  5. PAC-MAN & Galaga Dimensions
  6. DEAD OR ALIVE Dimensions
  7. Asphalt 3D
  8. LEGO Star Wars III: The Clone Wars
  9. nintendogs + cats: Golden Retriever & New Friends
  10. Rabbids Travel in Time

Top 10 Nintendo DS Games
August 2011

  1. New Super Mario Bros.
  2. Phineas and Ferb: Across the Second Dimension
  3. Pokémon White Version
  4. Cars 2: The Video Game
  5. The Smurfs
  6. Pokémon Black Version
  7. Mario Kart DS
  8. Plants vs Zombies
  9. Mario vs. Donkey Kong: Mini-land Mayhem!
  10. LEGO Pirates of the Caribbean: The Video Game

Top 10 Wii Games
TTM August 2011

  1. Just Dance 2
  2. Donkey Kong Country Returns
  3. Michael Jackson The Experience
  4. New Super Mario Bros. Wii
  5. Disney Epic Mickey
  6. Zumba Fitness
  7. Wii Fit Plus Bundle
  8. Mario Kart Wii
  9. Just Dance
  10. uDraw Studio

Top 10 3DS Games
TTM August 2011†

  1. The Legend of Zelda: Ocarina of Time 3D
  2. SUPER STREET FIGHTER IV 3D EDITION
  3. Pilotwings Resort
  4. LEGO Star Wars III: The Clone Wars
  5. RAYMAN 3D
  6. Resident Evil: The Mercenaries 3D
  7. nintendogs + cats: Golden Retriever & New Friends
  8. LEGO Pirates of the Caribbean: The Video Game
  9. Tom Clancy’s Ghost Recon Shadow Wars
  10. Super Monkey Ball 3D

† Since March 2011.

Top 10 Nintendo DS Games
TTM August 2011

  1. Pokémon White Version
  2. New Super Mario Bros.
  3. Pokémon Black Version
  4. Mario vs. Donkey Kong: Mini-land Mayhem!
  5. Mario Kart DS
  6. Super Scribblenauts
  7. Pokémon SoulSilver Version
  8. Sonic Colors
  9. Super Mario 64 DS
  10. Pokémon Ranger: Guardian Signs

Link