The top facebook apps are listed here.
Ignore the first one (UADA), its some sort of association of smaller developers.
Oh, and you can ignore their ‘valuation’ figures, which the industry generally regards as being nonsense. 
Daily Motion has begun offering some HD videos on its video sharing website. There’s not much there right now, but its sure to grow. You’ll need a fast internet connection to view it though.
I was recently taking a look at which data is mandatory and which is optional when people sign up to some common social networking and file sharing websites.
The attached table summarises what I found.
We all sense that a website should collect only the data it needs, and that the more data it tries to collect the more it may turn off potential users (concerns of privacy, etc). But as business people we also have to balance this with the need to add value to user signups (i.e. more data to help us profile users and deliver to them info and offers that are relevant).
It seems like the amount of mandatory data varies between 2 and 6 items (from simple email and password, to things like zip code, town, gender, country, DOB, occupational status).
The marketeers want as much data as possible, the technicians and user advocates want less. One would think that well-known sites are probably able to ask for more data and people will still not be put off, but younger sites who do not yet have repuation may need a more softly softly approach to data collection. Perhaps one way to satisfy both user and business needs is to take only minimal (eg email and password) at signup, but then incentivise the user to add more info, not with monetary reward but perhaps by unlocking site features.
