Dropbox - Online Sync and File Sharing
FileMenu Tools - FileMenu Tools lets you customize the context (right-click) menu of Windows Explorer.
Google Drive - Access and sync your files anywhere
Easy Context Menu - Easy Context menu is a Freeware portable utility that includes useful tweaks for the context menus.
ownCloud - ownCloud is an open source project enabling businesses to host their own cloud storage while maintaining regulatory and compliance needs.
Shell context menu manager - Powerful and lightweight context menu manager for Windows File Explorer.