ntfy.sh | Send push notifications to your phone via PUT/POST
https://ntfy.sh/
ntfy (pronounced notify) is a simple HTTP-based pub-sub notification service. It allows you to send notifications to your phone or desktop via scripts from any computer, and/or using a REST API. It's infinitely flexible, and 100% free software.
Mozilla developing Web push notification system for Firefox
http://arstechnica.com/business/news/2012/02/mozilla-developing-web-push-notification-system-for-firefox.ars
Mozilla is developing a push notification system for the Firefox Web browser. It will allow users to receive notifications from websites without having to keep those sites open in their browser. The system will also be able to relay push notifications to mobile devices.
Introducing Push Notifications
http://jbalogh.me/2012/01/30/push-notifications
Push notifications are a way for websites to send small messages to users when the user is not on the site. iOS and Android devices already support their own push notification services, but we want to make notifications available to the whole web. We’re making prototypes and designing the API right now and want to share our progress.