Gtasktic

Gtasktic is an awesome todo manager that also syncs with Google Tasks.
Features:
-Offline access: you don't have to be connected to the internet to edit your tasks.
-Multiple todo list on the same page. Filter system on the lower left allows you to concentrate on one list.
-Calendar view: See all your tasks with a due date on your calendar.
-Great interface: Gtasktic strives to be not only useful but beautiful.