You're right, iChat is a darn cool application. Now that my wife recently bought a brand new MacBook with a built-in video camera, we've been having a good time with video conferences too, whether I'm just a few miles away in the Ask Dave Taylor office complex or across the country, thousands of miles away. The kids love it too!

But you're talking about the little line that shows up under your friends in the iChat Buddy List, like what's below my pal "spike" in this little slice of my own Buddy Window:

(the nicknames have been tweaked to protect the innocent here. Note the icon next to "pet", btw. That means the other person can do a video chat. By contrast, the green phone icon next to "Mac" shows that they can do a voice-only chat, but not video.)

Underneath "Spike" you can see the custom status message "Mobile (Hiptop)" but you can actually put anything you want there. The key is to click on the word "Available" immediately under your own name:

If you want to create a custom available message, click on "Custom..." immediately under "Available", as I have selected in the menu above. To create a custom Away message, click on "Custom..." immediately below "Away". I'll do the former to show you what happens:

It's rather subtle, but I'm typing in "trapped in a hotel room" and am only halfway at this point. Type in the message you want and press return. Now it's set as your available message (if you're available) or away message (if you're away and you've set it as your custom away message). Simple and easy.

Now, two additional important things to know. First, once you start adding custom messages, you'll want to know how to both delete custom messages you don't want to use any more (like I will when I'm not in a hotel room!) and how to ensure that your custom messages are saved for the next time you use iChat. Both can be done by choosing "Edit Status Menu..." and you'll see:

Make sure you have "Remember custom messages" checked so you can add your own selections to the menu, and from here you can easily add a bunch of new custom iChat status messages by clicking on "+" below the Available or Away boxes, and if you want to delete one, click on "-" after you select a specific message. Done? Click "OK".

One more cool tip. Look back at the Custom Messages menu in the earlier screenshot. Notice the middle choice: "Current iTunes Track". That's great fun too, and you can see how it tracks iTunes in the following screenshot:

Anyway, iChat's very cool, and now you know how to play with custom status messages to your heart's desire!