1. [NDS] Pokémon Diamond & Pearl – 1,644,066 connections
2. [NDS] Animal Crossing: Wild World – 276,900 connections
3. [NDS] Mario Kart DS – 261,265 connections
4. [WII] Mario Strikers Charged – 178,888 connections
5. [NDS] Metroid Prime Hunters – 164,687 connections
6. [NDS] The Legend of Zelda: Phantom Hourglass – 148,783 connections
7. [WII] Guitar Hero III: Legends of Rock – 122,367 connections
8. [NDS] Pokémon Fushigi no Dungeon Toki/Yami no Tankentai – 114,492 connections
9. [WII] Pokémon Battle Revolution – 107,597 connections
10. [NDS] Jump! Ultimate Stars – 95,772 connections

Wow, Guitar Hero III made it on the list after only one night on Sale.

Link