Hi Lani, we are up the road in Ruschlikon. If you would like to talk about the area then feel free to pm me. I have 2 boys 5 and 7.
There is a nice farm in Kilchberg at the top of the hill. Also the swimming pool (indoor) offers lessons.
Also I am sure there are karate lessons, on a wednesday I think. http://www.indonesiankarate.ch/index.php?id=88&type=98
I was going to try this for my son but it clashed with another class he had on wednesday. The lady speaks english.
The badi will be the place to be in the Summer, its a good way for the children to see thier school friends out of school I think. Down the road in Rüschlikon it is free to enter.
Sometimes local librarys are worth a look. I dont know if Kilchberg has a toy library (Ludo Thek) but the Geminder will tell you that.