In addition to all of that, one feature that I find particularly useful.. is the ability to Tweet my Outlook Tasks and Appointments.
OutTwit makes this almost painfully simple.
Follow these steps:

1. Go to your Tasks folder, select a Task.

2. Select “Retweet” from OutTwit drop down menu.

3. Change the tweet text if you’d like, and hit Update.

That’s all.
Along the same lines, you can Tweet your Appointments, Email messages.

How to receive reminders via Twitter
If you would like to get more fancy, follow these steps to receive reminders for your Outlook tasks, as Direct Messages in Twitter.

In order to do this, you’ll have to add rtm as your friend on Twitter. After completing the setup, follow these steps.

1. Pick a task from your Tasks folder.

2. Invoke Retweet command from OutTwit drop down menu.

3. Prepend the tweet text with “d rtm” and specify the reminder interval as needed. For example:

Twitter will send you a reminder for your Outlook Task item, as Direct message, at the specified time.

You can find more RTM commands here.