I've started taking the train down from the city to Redwood Shores where I work, and I'm hooked. One of my biggest frustrations about living in the Bay Area is that I was burning anywhere from 2 to 3 hours a day in a car just waiting...and waiting...and waiting.
Since CalTrain leaves from 4th and Market (right by a Muni stop), it's pretty simple for me to get there and catch the 8:07, which gives me an hour in the mornings to code or think or write. My company has a shuttle that goes from the Redwood City stop to our offices, which means that I get off the train and there's someone there immediately to drive me the 5-7 minutes to work. I'm at work by 9:30 most days, which is about what driving translates into for me. Going the other way, the 5:45 shuttle gets me to the station in time to catch an express to the city, meaning I'm home well before 7. Life is good, and I'm a LOT less stressed out.
The only downside so far is that it more tightly constrains my options in some respects, is somewhat expensive, and means I can't carpool with Jennifer to work any more. I'm going to have to look into the monthly pass option.
Trains! Who knew?