Dropbox - Online Sync and File Sharing
WeTransfer - WeTransfer is a free service to send big or small files from A to B.
ownCloud - ownCloud is an open source project enabling businesses to host their own cloud storage while maintaining regulatory and compliance needs.
Microsoft OneDrive - Secure access, sharing & file storage
Google Drive - Access and sync your files anywhere
Box - Box offers secure content management and collaboration for individuals, teams and businesses, enabling secure file sharing and access to your files online.