Don't agree with the whole "no such thing as a second favourite team" sentiment. The Leafs will always be my #1 team, but I'm also a fan of the NHL in general, not to mention a straight up fan of hockey period (watching and playing). I've always liked the Pens, such great players to watch over the years (Lemieux, Jagr, Crosby, Malkin, Francis, Coffey, Stevens, Letang, etc.). Really liked the Wings AND the Avs during their rivalry years (weird, I know), and have enjoyed watching plenty of recent Ducks teams as well. If the Leafs ceased to exist, I'd probably watch just as much hockey as I do now.
Outside the NHL I really like the CHL, especially the WHL and QMJHL. I catch Giants and Mooseheads games whenever possible (live in Vancouver, visit Halifax decently often), and am defintiely a fan of both teams.
Last but not least, I'm a huge team Canada fan in all international competitions, especially the WJCs and the Olympics.