Many of the newer metro or mass transit lines in larger metropolitan areas offer free wifi Internet access to their riders. This is highly beneficial for commuters that want to work on projects, catch up on emails, or instant message with coworkers or acquaintances while riding to or from work.
Commuting time on mass transit can either be spent relaxing, waiting, or being productive. I would recommend either the first or last option! Relaxing can include reading a book, talking with friends, knitting, or even just taking a nap.
As far as the last option, being productive, there are several options, as mentioned earlier. Start by creating a to-do list of what you believe you can accomplish and work down the list as you are headed to your destination. Keep your enterprise instant messenger on do you can chat with coworkers about projects that you are working on. Maybe they are commuting too!