Pusher Beams - Send push notifications programmatically at scale
Task Coach - Task Coach is a simple open source todo manager to keep track of personal tasks and todo lists.
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
Strikethru - Strikethru is a kind of to-do list notebook for managing work lists and staying updated with the important tasks.