CBC Radio 3's site is amazing, with a staggering amount of music (streamed online free) from great Canadian bands. It's not easy to browse the bands and tunes, though -- almost impossible, actually. Here's a playlist including many of my favourites, mostly rock (Wintersleep, Matt Mays, Weakerthans, etc): http://radio3.cbc.ca/play/headspacej. It's not in any real order, so you can just shuffle at will -- 40ish songs I'm into right now.
Update: And on the theme of incredible Canadian content available free through our government-funded media bodies, I was so happy to see this news today: NFB makes films free online. I guess this should have probably happened earlier, and I wish they were all available now, but this start is still pretty great. Tons of fascinating Canadian films, including animation, documentaries and experimental stuff, and they're adding 10 more each month. The site was very slow today, but I suspect they'll work the bugs out soon enough.