Detect invisible people on yahoo messenger..

When a user seems offline, in fact he/she may be online but with Invisible status (avoiding you?), but Yahoo! Messenger will show him/her as offline (the gray face icon).

Here is a site which would tell you the actual status of the concerned user.
INVISIBLE

There are many spywares and small softwares available on the internet for this purpose but i don't recommend them as they may expose you hackers and let them know your passwords. So avoid using such softwares and just visit the above site.