Pusher Beams - Send push notifications programmatically at scale

EssentialPIM - EssentialPIM is a free Personal Information Manager that keeps up with the times and lets you manage appointments, tasks, notes, contacts, password entries and email messages across multiple devices and cloud applications.

Pingy - Check your site status from your menubar

Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.

Snowball Smart Notifications - Get the notifications you want and none of the rest

Task Coach - Task Coach is a simple open source todo manager to keep track of personal tasks and todo lists.