iZooto - Engage your mobile and desktop web users with intelligent web push notifications.
PushCrew - Push Notifications for Websites
Roost - Web Push has 30x better opt-in than email. Increase engagement with your audience using web push notifications
Pusher Push Notifications API - Send push notifications programmatically at scale
PushPro - Send Push Notifications from any website to mobile devices
Chrome 42 - Google's web browser now offers native push notifications