We blogged about the Gmail helper API in November, and the good folks at Remember The Milk have used the API to add tasks to the Gmail interface in a nice mashup:

Yup, that’s RTM in there! Remember The Milk for Gmail is a Firefox extension that lets you do all kinds of crazy cool things with your tasks (and interacts with your mail, contacts, and calendar too).

It goes beyond letting you manage your tasks, as you can connect tasks with your mail, google calendar, and contacts.

Watch the screencast to see it in action.