Snarl - Snarl is a notification system for Windows.
Zoom - Equip your team with tools designed to collaborate, connect, and engage with teammates and customers, no matter where you’re located, all in one platform.
Notifu - Notifu, a free open source pop-up balloon utility
Hubgets - Chat, voice, and video turning team communication experience into knowledge to help your business get more productive
Notify OSD - Canonicals on-screen-display notification agent, implementing the freedesktop.
Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.