Those traveling, or multi-computer using types, may be interested in Sky Drive, a new beta release of an on-line storage system from the Microsoft Live project. Whilst the 500 MB of storage is modest, it is the ability to limit access through encryption, to private, share with your family or group or even share publicly to the world, that may appeal. If you have a Hotmail account or a Passport ID sign up and give it a try.
A 500 MB memory stick is cheap these days and may be better and more flexible way to backup of photos while traveling, yet it doesn't give you the ability to instantly share, with good control over who too, or give protection should you and/or your luggage have an accident, get damaged, stolen, any of a thousand mishaps. Remember the memory stick will be there with you or in your luggage, and probably suffer the same fate. Memory sticks are also notoriously easy to loose.
On-line storage systems give you an instance off-site backup, but if 500 MB is not big enough you could consider the formal on-line backup systems like Mozy (which offers 2GB free) or Carbonite ( with has a 15day free trial), both offer unlimited storage at reasonable monthly fees. However both require a piece of downloaded software to run on your computer, are easy to automate and probably require a decent broadband connection. Sky Drive on the other hand can be accessed from any cybercafe or "free" (and thus slow) wireless hotspot on an ad-hoc "need to use" basis.