With software as complex and feature-heavy as Microsoft Outlook, it's easy to remain unaware of everything it can do. One of the Outlook features people still seem surprised about when I tell them is the fact that you can drag and drop an email to transform it into a task or meeting request. I use this feature many times each day and while Outlook's Tasks program isn't the greatest in the world (that honor goes to TaskPilot), it's fairly powerful and awfully convenient if you already use Outlook most of the time.
Since most of the tasks I perform arrive via email, using the drag and drop method saves me from having to re-type information and, more importantly, because it's so easy I'm highly motivated to use it. This makes it almost impossible for me to forget to do something. A sidenote here: When someone calls me and asks me to do something, I will often ask them to send me an email about it instead. This might seem a little rude to people who prefer the phone, but it's really the best way to ensure everyone ends up getting what they want.
To use this feature, just select the email that has all the information you need, drag it over to the navigation pane (probably on the left of the Outlook interface) and drop it onto the "Task" button (click the image over there to see what I mean). A new task will pop up with the same subject as the email and the contents of the email in the task's body. The due date and start date of the task will default to today, the status to "Not Started," and the priority to "Normal." You can edit all this, as well as the Subject, save it and you're done.
The same thing can be done with the Calendar, however it will usually require more cleanup since it's likely you'll be sharing the meeting with other people.
The only real problem with this method is that attachments to the email don't automatically get attached to the task. However, I found a workaround for this using macros. I won't get into all of it because someone else already has here. If you know a little VBScript or are willing to get your hands a little dirty to figure it out, you can customize that macro to your heart's content. Then you just add the macro to your Outlook toolbar and any time you get an email with attachments relevant to the task, click the button and voila, the attachments automatically show up in the task!