Here's an interesting light rail line found here in Ottawa that I'll share for people who might not know about it. It is a short rail line that is about 8 kms long (or 5 miles), and has 5 stations. It started as a pilot project in 2002 and has remained unchanged. This line uses the German-made Bombardier Talent trains (which is the only user in North America). It is integrated with Ottawa's transit agency, OC Transpo.
The O-Train is really an oddity compared to other light rail lines found in North America. Not only is it short, but it does not serve the city centre core directly, but does provide an easy bus rapid transit connection at its northern terminus (Bayview), as well as a connection to a bus going to the airport at the southern terminus (Greenboro); this is due to using old freight tracks which was cheap to install. The entire line is single tracked, with passing tracks at the middle at Carleton University. Two trains runs on a frequency of 15 minutes, passing each other at Carleton. This line also does not seem to serve anything, however because it stops at Carleton University I notice many students use it. It was supposed to be expanded, but we don't always know what the city council are up to.
I personally try to ride these trains whenever I can. I take the same bus from my house, to the University where I study, as well as the airport. To avoid the busy city centre, and having the bus stopping and going, I'll take the train...and often get on the same exact bus I got off earlier!
Here are a few links for more information:
http://en.wikipedia.org/wiki/O-Train
http://www.youtube.com/watch?v=lFLCq75mqMc
http://www.youtube.com/watch?v=xSbVkidAbgk