Outlook type task manager alternative for those using Zimbra

Jake over at Senokian put me onto Toodledo, a free online tool that has a Firefox plugin


Its not open source, but  its a useful interim tool for those (like me) that rely heavily on the GTD (getting things done) system of time management, but dont have outlook task manager (I am moving away fromall outlook v shortly) and know that Zimbra dosnt yet support tasks (why?????)

Off topic, its an excellent book and system by the way.