Facebook chat is one of the coolest and most useful features in FB. My dilemma, however, was how to limit the number of people I chat with every time I log in. I certainly can’t accommodate them all but I don’t want them to feel like I’m rejecting them when I don’t send them a reply. I didn’t know back then that it is possible to appear online only to a few selected friends. A friend of mine actually gave me this idea which I’m sure would be of use to you, too.
Here’s how to do it:
Go to Chat found at the lower right side of the page and then, click on gear icon and click on advanced settings. A window would pop-up, now in the field which says “Turn on chat for all friends, except..” start adding your friends name, for whom you don’t want to appear online. With this, you now appear completely invisible to them. Try it now.