Imagine you're away from work, all you have is your work laptop, and you want to look at porn. Not a good idea, right?
Browsers have recently introduced features to help this (Chrome's "Incognito", IE's "InPrivate", Firefox's "Private Browsing", etc). However, they do nothing to prevent data from being placed on the swap partition. With the existence of tools like PhotoRec, it's very easy to grab photos out of swap.
One possibility is to set up Linux inside VirtualBox, and encrypt everything, including swap.
TODO: question: does VirtualBox ever use physical disk to provide extra virtual RAM? (in effect, providing an additional swap layer) If so, this "feature" would need to be disabled.