As I was sending an e-mail today, I wondered if there were any easy way to choose my outgoing account in Mail. Like many people, I have several accounts, and need to choose specific ones for messages I send to certain clients. So I wondered -- since you can apply keyboard shortcuts to menu items using the Keyboard Shortcuts tab of the Keyboard & Mouse preference pane -- maybe that would work for this drop-down menu in Mail.
So I went to that preference pane, clicked the Keyboard Shortcuts tab, and clicked the + button to get the new keyboard shortcut dialog. I chose Mail as the application, then entered the exact information that displays for one of my accounts (in the Mail 'From' drop-down menu). The format of each menu item is:
First_name Last_name <my_email@my_host>
Make sure to include the angle brackets, and put a space before the first one. Choose a shortcut -- I chose Command-Option-Control and a letter for each account -- then click Add. As you can see from Rob's screenshot, it works as expected.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20081120093222315