I use my laptop to do home projects or writing (eg for InfoQ or books/blog posts). The trick is to be able to partition work and be able to stop and start quick

I use my laptop to do home projects or writing (eg for InfoQ or books/blog posts). The trick is to be able to partition work and be able to stop and start quickly - plus to use a laptop efficiently you need to be able to get a table seat and a power socket. If I'm not travelling with my laptop then I will typically read a book or magazine. You might also find noise cancelling earphones and a supply of music useful if you have noisy fellow commuters, but it's not strictly necessary.