If you're running OS X 10.5, you're probably aware of the new "data detectors" feature in Mail (and in iChat via a Terminal command). Data detectors see dates, times, and addresses in e-mails, and provide the ability to add those items to iCal or your Address Book, as appropriate.
When Mail's data detectors find a date or time in the body of an e-mail, a dashed box and drop-down arrow will appear when the mouse hovers over that data; click the mouse, and a drop-down menu appears with two options: Create New iCal Event and Show This Date in iCal. If you choose to create a new iCal event, a dialog box that resembles the standard iCal "add an event" box appears as a pop-up within Mail. Enter the event's location, calendar, alarm, and other data, then click Add to iCal to send the event off to iCal.
While this is very useful, there are some limitations. The pop-up box in Mail lacks some of the fields you'll find in the same box in iCal--attachments, attendees, and URL are all missing, for instance. Also, you can't add multiple alarms to events created with this dialog box in Mail. To do these things, you'd typically add the event to iCal, switch to iCal, find the newly-added event, and then edit it as needed.
But there's a better way, thanks to the power of the Option key--and you have not one but two chances to use it in Mail (and in iChat, if you've enabled data detectors there, too). If you know right away that you'd like to use iCal to edit the event you'll be adding from Mail, press and hold the Option key before clicking on the triangle in the data detector box. With the Option key held down, the pop-up menu will read Create New Event in iCal (instead of Create New iCal Event). When selected from the pop-up menu, iCal will launch (if it's not running), and then create a new event based on the information you clicked on in Mail. Click the Edit button to edit all the typical iCal fields for an event, then click Done.
But what if you didn't realize you wanted all the data fields when you selected the Create New iCal Event menu item? As it turns out, you can press Option even after the new event dialog box is on the screen--when the Option key is down, the Add to iCal confirmation button will change to read Edit in iCal. Click that button, and the event will open in iCal, where (annoyingly) you still have to actually click the Edit button to edit the entry.
In either case, using the Option key is a nice timesaver when compared to manually switching to iCal and finding the event you've just added.
This story, "Edit Mail's Data Detector ICal Events in ICal" was originally published by Macworld.