Laptops get lost and stolen a lot. I am extra careful with my laptop because I keep so much of my and my customer's private data on it. I take a few steps to protect this information that I want to share with you (Mac OS X specific):

I keep a small encrypted disk image that contains all my passwords and other sensitive information. It also contains my .ec2, .s3cfg, .profile, .ssh, .gnupg, and .heroku files. Then in my home directory I make soft links ln -s ... to these files.

I do not keep the password for this disk image in my OS X keychain!

It is a very small hassle: each time I boot up, I mount this image so my .ssh, etc. files are available. This adds 10 seconds of "overhead" to each time I boot my laptop.

Whenever I start working for a new customer, I ask them if they would like me to also keep their working materials encrypted (some overhead involed, so I like to ask them if I should spend the time doing this).

Update: a reader pointed out that this is only a partial solution, and I agree with that. Using full volume encryption is a much more secure system. With my easy scheme, for example, browser session cookies are vulnerable so someone might be able to access your gmail account and any services that use email password resets.