Mengecek User YM Online atau Offline
Quote from:
http://arun.wordpress.com/2006/02/12/yahoo-msngr-breakthrough-the-stealth-settings/
This article will show you how to know if you are being marked Permanent offline by a buddy. I have tested this method using Yahoo Messenger 7,0,0,437
Well you can know if a buddy is online and has marked you permanent offline only if the guy has signed into yahoo in Available mode and NOT if he has signed as Invisible..
Here is how to proceed..
Visit any of the following links replacing the [username] with the required yahoo id..
- http://mail.opi.yahoo.com/online?u=[username]&m=g&t=0
This will show you as a yellow smiley if the person is online and gray if the person is offline or invisible. - http://mail.opi.yahoo.com/online?u=[username]&m=g&t=1
This will show up as a button with “Online Now” or “Not Online“ - http://mail.opi.yahoo.com/online?u=[username]&m=g&t=2
This will show an image (125×25) with “I am Online send me a message” or “Not Online right now“ - http://mail.opi.yahoo.com/online?u=[username]&m=a&t=0
This shows a text with “[username] is ONLINE or NOT ONLINE“ - http://mail.opi.yahoo.com/online?u=[username]&m=a&t=1
This shows “00” if person is offline and “01” if his status is online.
All the above links can be used as an Online Status generator (with some PHP offcourse) and also you can write up a small code to know if a particular guy is hiding from you 
Finally sometimes this method may return wrong results (if there is some problem in yahoo server) and if someone appears online to you but is offline as per this method then know that the guy has signed in as invisible and is appearing as online to you only (may be coz you are some one special )
Note : It always shows incorrect Yahoo id’s as offline..Do check the yahoo id carefully !!
Example : If your yahoo id is xyz..Try this method by using the url : http://mail.opi.yahoo.com/online?u=xyz&m=g&t=0
