I just got my NEXUS pass a few weeks ago, and the line up during the BC day long weekend was over 2.5 hours at Peace Arch, the line up started at the last HWY entrance, (over 1KM long). My wait was just one car, or about 20 seconds.
Cost $50 (US) per person, and 16 and under are free. The NEXUS is good for 5 years plus your next birthday. So say that your B-day is on Sept 2nd, 2008; and you get your NEXUS pass on Sept 1st, the NEXUS pass will expires on Sept 2, 2013, but if you get your NEXUS pass on Sept 3rd, then your pass will expire Sept 2, 2014.
Everyone in your car must have a NEXUS pass, the rules have changed, you CAN NOT drop off anyone without a NEXUS pass at the border and walk across (I thought about this as well). Everyone must have a NEXUS pass, otherwise you must line up like everyone else. When you pick up your NEXUS pass, they will tell you this, as well as that you must declare EVERYTHING you bought in the United States; even a cup of coffee that you did not finished, that is sitting in your cup holder.
You can sign up for your NEXUS pass on-line, here is the link
https://goes-app.cbp.dhs.gov/Takes about 8 to 14 days (the web site says it can take up to 6 weeks) to process your application. When you're approved, then you will need to make an appointment to get your NEXUS pass. If you go to the Vancouver airport, the wait time is about 2 months, if you go to Blaine, WA, the wait time is about 3 days. If your b-day is coming up, then book the appointment after your b-day to get the extra year.

When you show up for your appointment at Blaine WA, it's like going to renew you driver license, you stand behind a bench type desk, and they will just reconfirm your information that you submitted in. The NEXUS office in Blaine is right after you cross the Pacific HWY crossing, just tell the border guard and he/she will give you instruction on how to get to the office.
Is the NEXUS pass worth $50 for 5 years? That's only $10/year. If you like to travel, fly out of Bellingham (Allegiant air) or Seattle ONCE and you will save OVER $50 there alone.