Posted: Fri Aug 15, 2008 8:10 pm-
If you're aged between 18-30 you can easily get a cheap working holiday visa that would allow you to stay and work in Australia for up to 12 months. It's probably the easiest way to get in although you're expected to arrive with a return plane ticket, so you really don't want to arrive at the airport and say you're planning on marrying your Aussie boyfriend because that wouldn't go over too well!
http://www.immi.gov.au/visitors/working-holiday/417/index.htm
You might have other options as well depending on your situation.
If while you are in the country you decide to get married then you can apply for a spousal visa.
http://www.immi.gov.au/migrants/partners/spouse/820-801/index.htm
Or if you know you are likely to get married then you could apply for a prospective spousal visa while you are still in Canada. That will give you a 9 month window to enter Australia and get married.
http://www.immi.gov.au/migrants/partners/prospective/300/index.htm
Or, if you've been living together for the last 12 months then you could apply for an offshore defacto spouse visa:
http://www.immi.gov.au/migrants/partners/spouse/309-100/index.htm
Hope that helps. You'll need to read through all the visa options on the immigration website to see what works best for you.