Y Informer 3.3.100
This program will allow you to scan your YM buddies or any YID to see if they are online, even if they are in invisible or stealthed! It also has the option to see if the target has their webcam being broadcasted in Yahoo Messenger.
YInformer has several different scanning methods to choose from that are highly accurate when the right one is used and YInformer is clean, compact, easy to use, full of options and fully supported!
YInformer has primarily been used to see if your YM buddies are online (but invisible) but has expanded to any YM user, not just someone on your buddy list. YInformer has also been used to track cheating (or suspected of cheating) spouse/significant others.