Remember the Milk for Gmail is a super cool Firefox add-on which integrates a task manager into your Gmail service. You’ll recognise the name from the original RTM proglet, but this new version really does have some clever bits going for it. For starters the integration with Google is really tight, so you can link tasks with contacts, connect a task with a particular email (e.g. find out flight details and email back to Ian by Thursday) and even connect Google calendar automatically to tasks. It’s all rather swish and very well done, although the interface is probably a little more complex than it needs to be. Definitely worth checking out nevertheless.
Remember The Milk for Gmail is a Firefox extension that allows you to manage your tasks in Gmail (complete, postpone, and edit tasks), add new tasks (and connect them with your emails, contacts, and Google Calendar events), automatically add tasks for starred messages or specific labels, and much more!