The Pansonic ToughBook range of laptops are designed to stand up to a lot of abuse out in the field, and are favoured by those working in harsh environments for this reason. The following article gives some interesting insight into the testing process behind these laptops at Panasonic's facilities in Japan:
Zen And The Art Of ToughBooks : http://www.trustedreviews.com/notebooks/review/2007/02/06/Zen-And-The-Art-Of-ToughBooks/p1
Impressive stuff, I might be in the market for a new laptop next year but I am not sure that I will be prepared to fork out for the high price-tag on a ToughBook.
Updated 2021 : note that the above post is out of date as it was originally published in 2007, but is left here for archival purposes. Unfortunately the external link is now dead, so I have unlinked that.