http://www.republicwireless.com/
Basically, you pay $199 for an Android phone. For each month after the first, you pay $19 for unlimited talk, text and data. The key is the phone uses wi-fi whenever possible to transmit and receive. If you leave an area that doesn't have wi-fi, the phone switches over to traditional cellular service.
The fine print says that you have to abide by the fair use limits set by the community. If you use cellular service too much relative to your wi-fi use, they will "help" you find a traditional cell phone service provider. It sounds like you can consume up to 550 minutes of talk, 150 texts and 300 MB of data on a cellular line before they raise concerns.
You are also limited to just the one phone they offer: the LG Optimus running "Gingerbread" (Android 2.3).
The company is based in North Carolina so you probably can't use this service in Canada.