I found and actually using Dropbox to save files online.
Several reasons to use for:
- All data is transferred over SSL and encrypted with AES-256 before storage.
- You decide with whom you want to share files and wich files.
- Only files in a "public" foldder can be linked.
- If you have more than one computer, you can use dropbox on all computers and synch your fils via dropbox
- Dropbox is also smart with how it tracks changes to files. Every time you make a change, Dropbox only transfers the piece of the file that changed (also known as block-level or delta sync), making it easy to work with big files like Photoshop or Powerpoint documents.
I tested it on XP and Vista.
As long as it is free with 2 GB online storage, I can recommend it. (Maybe for storing a years tracks online or screenshots or whateva

More infos and download:
http://www.getdropbox.com/