Although Ontario is where most of the big non-for-profit organizations are based, Vancouver has its fair share of charitable organizations that are always looking for good people with big hearts.
Some resources for Vancouver:
The Vantage Point (formerly called Volunteer Vancouver) — a listing of non-profit organizations. A good way of figuring out what organization you might be interested in working for is to volunteer with them.
VancouverYouth.ca offers a comprehensive listing of all the youth-related organizations in the city.
Directions Youth Services Centre provides services to homeless or at-risk youth.