Nintendo DS

1. Pokémon Diamond & Pearl - 1,524,670 connections*
2. Animal Crossing: Wild World - 348,914 connections
3. Mario Kart DS - 324,153 connections
4. Metroid Prime Hunters - 148,422 connections
5. The Legend of Zelda: Phantom Hourglass - 137,045 connections
6. Yu-Gi-Oh! Duel Monsters: World Championship 2008 - 126,690 connections
7. Ryuusei no RockMan 2: Berserk x Dinosaur/Shinobi - 123,491 connections**
8. Jump! Ultimate Stars - 94,994 connections
9. Pokémon Fushigi no Dungeon: Toki/Yami no Tankentai - 78,161 connections***
10. Dragon Quest Monsters: Joker - 74,910 connections

* Diamond - 906,467 | Pearl - 624,221
** Shinobi - 67,161 | Dinosaur - 56,355
*** Toki - 42,010 | Yami - 36,151

Wii

1. Guitar Hero III: Legends of Rock - 1,164,926 connections
2. Mario Strikers Charged - 183,087 connections
3. Pokémon Battle Revolution - 177,830 connections
4. Medal of Honor Heroes 2 - 99,856 connections
5. Mario & Sonic at the Olympic Games - 92,269 connections
6. FIFA 2008 - 48,609 connections
7. Dragon Ball Z: Budokai Tenkaichi 3 - 39,327 connections
8. Madden NFL 2008 - 36,023 connections
9. Sonic Riders: Zero Gravity - 24,791 connections
10. Rayman Raving Rabbids 2 - 24,704 connections

(via neogaf)