I signed up for this service after a friend recommended it to me, and I must say it's pretty sweet. I really like the fact that they have Windows, Mac, and Linux client software that lets you integrate the service so it appears as a local storage location on your computer. I've got it installed on my Netbook and my Notebook, they both have Ubuntu Netbook Remix installed. I currently don't have access to my Hackintosh system or my Windows 7 gaming PC but I'll be installing it as soon as I can go pick them up and bring them to where I'm currently staying.
Here is a referral link to sign up for the free service if you are interested. If you use my link I get a free additional 250 megabytes of storage space, and you also get an additional 250 megabytes of storage space added to your dropbox account.