Snarl - Snarl is a notification system for Windows.
Notifu - Notifu, a free open source pop-up balloon utility
Growl for Windows - Growl for Windows is a Windows-compatible version of https://alternativeto.
Notify OSD - Canonicals on-screen-display notification agent, implementing the freedesktop.
notify.uno - Get notified when your commands are done.
Notify17 - Notify17 lets you generate notifications with simple web requests, and you can receive them on Android, iOS and the Web.