My routine as follows:
Read emails
Read blogs and geek websites
Polish up on Rational
Watch day time TV, (try not to commit suicide)
Exercise
Think about picking up weighty testing practioneer book (think day time TV is probably less dull)
Read some more emails
Look at jobsites
Wait for next project
Become very bored
Read article about offshore testing market expanding
Pick up that book 🙂

I know you mentioned that when you are working for a customer that you concentrate on solving their problems, but I’m curious as to how much of the other things you still try to fit in. I have a full time job and have two kids under the age of three. As you expect, I have much less time to stay sharp – but still think exercising the brain is extremely important and I’m curious what you do to stay sharp *while* you’re consulting. I, of course, realize that it’s not an entirely apples to apples comparison as your clients may have different expectations from you while you’re working than a full time employer does.

As an example, last week (in addition to my day job), I did these things to stay sharp:
– solved 2 problems from project euler (www.mathschallenge.net)
– reviewed 2 chapters in the Schaum’s discrete mathematics outline
– read “The Wisdom of Crowds”
– Re-read various Richard Feynman essays

I also read a handful of testing articles and chapters from testing books, wrote some sample code for a course I’m teaching, and did some research on Customer Focus Design, but fortunately, I consider that part of my job and did most of it while “on the clock”.