In the last week I have taken two flights, rode in a bus and on a train.  While on these three modes of transportation I evaluated what type of work could I get done.  How productive could I really be while in transit from one place to another.  I usually sleep on a flight or in a train ride, but recently I have tried to make that time productive.  

I have not been lucky enough to be on a flight with internet as of yet.  So my productivity is limited to what I can sync offline and finish while in the air.  I used my time on a flight from London to Barcelona to answer emails and work on blogs posts.  Once we landed I connected to the internet and synced my emails and sent out my blog posts.  This was a pretty good use of the three hour flight to Barcelona, considering I would usually have slept that whole flight.

On the train I had my broadband card so I was able to access the internet to work on a client proposal and record a screencast for an application.  The train was nice because the seats were spacious and if you get on the train a bit early you can get a seat with table.  The hardest place for me to work was on the bus.  The bus was really cramped and extremely difficult to work on.  The space was too small to try to work on my laptop and the ride was bumpy making it really hard for me to read because I get motion sick.  So I used the rest of the bus ride to catch up on some sleep.  So at the end of it I got some sleep but realized that I can be pretty productive on a train or plane.  

What do you do while in transit to stay productive?  What type of work do you do on planes, trains and buses?