iChat AV: HAVE ICHAT ANNOUNCE YOUR BUDDIES

If you want to have iChat automatically make an audio announcement when one of your buddies logs on, it's easy. Just click on their name in your Buddy List, then press Command-I to bring up their Info dialog. Choose Actions from the Show pop-up menu at the top of the Info dialog, and you'll see a list of alerts you can have go off when your buddy logs on. At the bottom of this list is a checkbox for Speak Text. If you turn that checkbox on, click in the text field and type the message you want spoken by your Mac.