Commuting Time - Productive?

As I spend around 3 hours of my day on a train commuting I found this article by Dave Burke very interesting. It shows that with the right technology it is possible to be productive even when you re travelling.

Official Google Blog: 20 percent time spent coding in the clouds

In the past I have typically used the time on the train to read or sleep but due to the better mobile data plans I am able to login to services such as App Inventor to  develop applications for my Android phone.

Now instead of 3 hours of wasted time I can be productive.