ToDoTweet is a very simple to use Free Task Manager that lets you create your To Do list by just sending Tweets. ToDoTweet tracks hashtags in your tweet. If you send any tweet with a hashtag #todo, ToDoTweet will add that item to your To do list. ToDoTweet also lets you add categories to your to do items. For that, you can add another hashtag to your tweet that corresponds to the categories in which you want that item to go. This is the easiest way to create a to do list that I have come across.
To check your To do list, you can go to ToDoTweet website, and login with your Twitter account. It will show you the To do list that ToDoTweet created from your tweets. You can search the list by categories as well. ToDoTweet lets you mark items as completed, and also lets you create private to do items directly from website.[subscribe-to-us]
Having a Twitter based free Task manager is really good, as you can send tweet from almost anywhere. You can email tweet, tweet from your cellphone, or use some Twitter client. Irrespective of the method that you chose, your tweets will be accumulated in your online To Do list.
I really like ToDoTweet for its simplicity, and practical use. One thing I did not like is the fact that my tweets will be visible to everyone. Instead, it would have been great if ToDoTweet could work on direct messages, in the same manner as TweetWhatYouSpend does.
If you want an online to do list, you can use Toodledo.