Ques 1. What is Yahoo Tracker?
Ans. Yahoo Tracker is a web based service that allows you to track online/offline status of your yahoo buddies.
Ques 2. Can i track those who are not in my messenger list?
Ans. Yes you can, your yahoo username and password are not required to use this service.
Some more features about this service--
1. The service tracks the online/offline activity of Yahoo messenger user in previous 24 hours.
We might increase the time period to 1 week in near future.
2. You can track 12 yahoo users with one account. Yes its all free..!!
3. Data will be updated after every 10 minutes automatically.
4. Yahoo messenger 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.
So, enjoy Yahoo Tracker ALPHA by simple registration::::

http://www.yahootracker.com