Dropbox

If you haven’t tried it, take a look at Dropbox. Installing the software adds a special folder to your Mac or PC: put your files in it and it works like a regular folder, except it also backs them up to the web. So that means you can retrieve those files with just a web browser from another computer. It does other backup, syncing, and mobile tricks, but that’s the main idea. The free account gets you 2 GB.