PushCrew - Push Notifications for Websites
/Tab - The simple way to split a bill among friends.
OneSignal - Customer engagement platform used by over 1 million developers and marketers; the fastest and most reliable way to send mobile and web push notifications, in-app messages, emails, and SMS.
Splitwise - Splitwise is a free tool for friends and roommates to track bills and other shared expenses, so that everyone gets paid back. On the web, iPhone, and Android!
iZooto - Engage your mobile and desktop web users with intelligent web push notifications.
Splittable - Shared living made simple