I love instant messaging, but even I agree that you need to block strangers from interrupting you. Steve Bass at PC World sketches out how to be invisible on IM. Personally, I don't have a boss, and I like to let my contacts know when I am idle -- usually means I am on the phone or otherwise busy.

Cloak of Invisibility

The Hassle: I love instant messaging, but I hate it when strangers interrupt me. Plus, my boss can tell when I'm away from the PC. Even the alerts when buddies come and go are getting annoying.

The Fix: Become invisible. In AOL's full version of AIM, click Setup at the bottom of the window, choose Preferences, Privacy, and select Allow only users in my Buddy List. Don't want anyone to know you're goofing off? Uncheck how long I've been idle. To squelch the alerts, choose Notifications in the Category list, uncheck Show pop-up notifications, and click OK.

In MSN Messenger, choose Tools, Options, Privacy, highlight All others in the 'Allow list' pane, and click Block. Next, return to the options list, pick Personal, and under My Status, uncheck Show me as "Away". Then go back to options; and for Alerts and Sounds, uncheck all the boxes.

In Yahoo Messenger, choose Messenger, Privacy Options, Ignore List and then select Ignore anyone who is not on my Messenger List. Next, select Privacy and check Do not show anyone how long I've been idle. Finally, choose Alerts & Sounds, uncheck Enable alert sounds, and click OK. To cloak yourself from specific buddies: Right-click one of them, choose Stealth settings, and then select Permanently Offline.

I don't recommend going all the way fully cloaked in darkness, as outlined. But I certainly buy into ignoring those not on your buddylist. Even though time is a shared space, you need to share it with the world of those known to you, not some schlub in Turkey who wants to practice his english (it has happened, believe me) or yet another guy who wants to argue with me about the incredible value of LinkedIn membership.