Why this option needs a mention in this blog:
This is one of the most useful and also one of the most under-utilized option of yahoo messenger (one of the top 3 most popular instant messenger in the world, and my favorite)
Why should we use it:
Most people log in to invisible mode when they dont want to be disturbed by a few of their friends.
How to use it:
Create a group and move all your less important and disturbing friend to this group. Set the stealth setting so that you appear offline to all these people. You can still see them being online. You can intitiate a chat with them when you want to. Life should be much easier with them.