Wanna check if your Yahoo buddy is avoiding you and hiding using the invisible mode ? not anymore, there exist several web based and desktop solution to spy your yahoo buddy list.

YahooTracker

Currently in ALPHA this fantastic FREE online service allows you to track online/offline activity of Yahoo messenger users in previous 24 hours, You can track 12 different yahoo id’s with one account, the user activity is automatically updated every 10 minutes, users will be considered as online even if they are invisible to any number of people (not everyone). Being “on sms” and “on mobile” will also be considered as online.

InvisibleScanner

A easy to use online service to check Yahoo Invisible Status.
Yahoo Invisible Scanner >>

Buddy Spy

Buddy Spy is a free desktop software which can keep track of what other Yahoo Messenger! users are doing, even if they are in Invisible or Stealth Mode. The program shows if the user is online, what chat room they are in (if any) and if their web cam is online. It is able to do this by connecting to Yahoo! Messenger’s servers and using its YMSG protocol. Sending carefully crafted packets, and listening to their responses. Buddy Spy’s Feature list includes:
Stealth Checking
Room Checking
Webcam Checking

Spy Invisible Yahoo Users & Track Their IM Usage !

Download Buddy Spy >>

Alternatively you can also check the status using the manual method, just replace the YAHOO-ID-TO-CHECK with the original yahoo id you want to track in the url below:

http://mail.opi.yahoo.com/online?u=YAHOO-ID-TO-CHECK&m=g&t=0