I know there are at least two indoor playgrounds in Ottawa.
The biggest one is located in the east part of the town called Cosmic adventure. Please check the website below: http://cosmicadventures.ca/
The other one is quite new and just opened last December. It is located in kanata. You can find more info in the link below. http://www.kidszonefuncentre.com/
You also can enroll your child in some playgroup programs. I know Gymboree is very good. It provides a lot of music and play activities. Please go the link below to find more information. http://www.playandmusic.com/b2c/customer/home.jsp.
Ottawa's site info can be found there, which is close to Pizza hut at Richmond road.
Winter is also a good time to let your children enjoy outdoor acitivties, such as tobogan, skating and skiing sth.
You also can bring your child to drop-in centres close your home if your child is less than 6 years old. The drop-in centre is a good place for parents and children meeting together. You can check the website below to find out which drop-in is closest to you or most convinient for you. http://www.parentresource.on.ca/ottawadropins.asp