The best iDisk replacement: Dropbox!
This iDisk replacement is so good, that I use it instead of dotMac even though I pay for dotMac. The free account includes 2 GB of storage. The way it works is it creates a folder on your Mac that is synched back to the cloud and to every other Mac, Windows and Linux computers that it is installed on. You really have to give it a try to understand how great it is. You can even restore deleted files through the web interface. You just have to download the software and you can create your account through the app.