Good Wifi Games

What are some good wifi games for the DSi, like where there's a good amount of people playing at all times.
I'm interrested in Bleach: Dark Souls, I already have Pokemon Soul Silver.

Umm bumps

Mario Kart DS always has tons of people playing online, and it's a lot of fun.

there are way too many people cheating in Mario Kart DS though and that does ruin the fun.