I stumbled across Remember the Milk a couple of weeks ago. It's a web app to manage task lists with great integration with pretty much anything I use: You can email tasks to your todo lists from the blackberry, it supports iCal style export, it has an iPhone optimized app, plus there is a quicksilver plugin!

Apart from being very useful and saving you the pain of synchronizing task lists across platforms all the time, what I like the most about the application is its use of keyboard shortcuts that really boost your efficiency when dealing with the app. Haven't seen anything like it in a web app so far. So go check it out, it's free.

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