Can use RTM as todo list Rated 5 out of 5 stars
Google task won't show, but good things is Remember The Milk has a Google Calendar Sidebar Gadget: https://www.rememberthemilk.com/services/googlecalendar/sidebar/
The RTM Sidebar Gadget can be a great replacement for Google Task. And the best thing is it shows perfectly in Google Calendar Tab.
With the help of RTM's Sidebar Gadget, this addon becomes a killer addon for GTDer. Now I can see my emails, Google Calendar and Remember The Milk in 1 place.