Microsoft provides a free 25 GB through Skydrive.  Skydrive Explorer is a nice addition allowing you to copy files directly to your online storage through My Computer.   Microsoft has been one of the better providers of the ability to sync and share files across multiple computers through the cloud.  I have used LiveMesh exclusively, but with my school’s network, LiveMesh and DropBox do not sync.  They are great alternatives for a home network though.