If you haven't done this and you travel more than a couple of times a year out of either the US or Canada, run, don't walk to get your Nexus pass.
This program is a joint effort between the US and Canadian Border Security services. (There's a separate program for the US and Mexico) What you do is apply online. A security check is done and then you're invited to appear for an interview. You can do the interview at many places around the country but all the international airports in Canada do them.
The interview is just like going across the border but takes 5 minutes instead of 1. Then you pay your $50 (good for 5 years) and you've got your card.
Once you've got that card you no longer wait at immigration.
Ever.
At the airport you scan yourself through the iris scanners and you're on your way. At many of the Canada/US land crossings, there is a lane dedicated to the Nexus pass holders. This saved me about 3 hours once driving from Vancouver to Seattle.
If you've got a Nexus card, here's a tip that not everyone knows. It's good for entering Canda no matter where you're coming from! On my last connection from Australia through Vancouver to Montreal, this made the difference of catching or missing my connection.

US/Canada, US/Canada

Chris Vandersluis