This tip I got from the book Upgrade Your Life really helped me out on a recent trip to Mallorca. I took my beat up old macbook just to minimally keep up with customers questions and orders while visiting the Spanish island for 9 days.

Just before we left for the airport I was rebooting and my Macbook completely crashed and needed its system reinstalled. I took the install discs with me and when we got to our chateau on the coastal mountainside I reinstalled OS X and then was left with nothing but the default installed software.

I remembered that I had just signed up for and synched with Xmarks just before I left and gave it a go with a new download of Firefox on my laptop. It worked beautifully and my laptop had everything I needed to get to all my bookmarks and also remembered passwords which would have taken me forever to figure out.
Needless to say I’m a total Xmarks fan now.
http://www.xmarks.com/

(this is good for PCs as well of course)