Kung Fu Live on PS3 had tons of issues (eye toy game). Yet I played the endless stages regularly as an exercise game next to DDR.
Same for Shaun White Snowboarding on the Wii Balance board. Half pipe challenges had me sweating in no time. Good for squats!
Skyrim on PS3 :p I had to turn off autosave and restart the game every 10 - 15 minutes as it slowed down to a crawl 50 hours in.