Facebook Widget Installs Zango Spyware
“A malicious Facebook Widget actively spreading on the social networking site ultimately prompts users to install the infamous “Zango” adware/spyware. The tremendous success and lightning fast expansion of Facebook empowered the social networking giant with an impressive user base. Needless to say, in a digital world where web traffic equals money, such a user base attracts spammers, virus/spyware seeders, and other ethic-less online marketers like honey would attract flies.”
from Slash Dot
So Beware! 
Yes, there’s alot apps really sucks
you should beware! from Spywares