Fun Way to Send Attachments in Mail

If you're working in a file that you want to attach to a message in Apple Mail, you can transfer the file to Mail easily: From the title bar of the file's window, drag the little proxy icon to Mail's icon on the Dock. Your Mac will make Mail the active application and open a new outgoing message, with the file attached.

(If your icon won't drag, the file probably isn't saved.)