Sugarsync is an online file synchronization and backup service. The service is fee based, but they do have a FREE account option with up to 2GB of storage available. If you need more storage space, you can add more memory at very reasonable rates. Reviews in multiple tech magazines always give Sugarsync high ratings and it's fees are some of the lowest in the industry.
Sugarsync allows you to store files online and even keep the online files sync'd with the files on your computer. I love it because it allows me to have access to my files from any web-enabled computer. You can even access your files from a web-enabled cell phone or smart phone. I no longer have to have a flash drive with me to bring files home to work on.
You can even share file access with other people if needed.
Sugarsync is easy to sign up for and very easy to use. You can simply upload files to your Sugarsync account and access them from the web. I recommend installing the file manager on your main computer and then selecting the files that you want to be sync'd to Sugarsync's system. You will be able to access all of those files from any other web-enabled device. The service has built in security and has it's own backup system for your data.
The web access looks just like a typical file explorer on a computer, but it is all web based. You can download files, move them to other directories, send them to people, or even edit them using their WebSync technology. WebSync allows you to edit your files from any internet connected computer and have the changes automatically backed up to the SugarSync servers. This means that you do not to manually download the file, edit it locally, and then re-upload it to the server.
Backup copies of your files and access to them anywhere - for free. You can't beat that.