WeTransfer - WeTransfer is a free service to send big or small files from A to B.
BoxCryptor - Boxcryptor encrypts your sensitive files before uploading them to cloud storage services like Dropbox, Google Drive, Microsoft OneDrive, Box, and many others.
Dropbox - Online Sync and File Sharing
Mega - Secure File Storage and collaboration
Google Drive - Access and sync your files anywhere
Hightail - The professional way to send & share files and folders with anyone