There was a WiiWare game called "Water Warfare". It's an FPS game with water guns. Never played it, but the name alone draws interest.
Are there any Wii games that are similar to Call of Duty, but suitable for an 8 year old child? I see there is a Nerf game that was apparently designed for kids, but I don't think that a kid who only wants Call of Duty is going to be happy with a childish Nerf shooting game. Normally I'd go check out the gameplay of various Wii games on Youtube so I can get an idea of what the games are like, but sadly I'm stuck on an insanely slow internet connection right now.