Latest in Google projects developed within under its Slide series is the "VideoInbox," which is a daily newsletter as well as a Facebook app that basically centers around the viewing, sharing and cataloguing of viral videos.
Sign up for VideoInbox with Facebook Connect and you'll get a daily email with "hand selected" viral YouTube videos. The Facebook app uses, amazingly enough, the Facebook API to allow you to share videos with individual friends on Facebook or post them to your Facebook Wall. The app also allows you to watch the top 5 viral videos from yesterday, as well as "Favorite" videos for watching later.
While the button is there, its Twitter OAuth aspect seems to be not yet implemented.
Slide has been super productive since Google acquired it for $182 million back in August, coming out with a series of iOS apps including Photovine, Pool Party and group messaging app Disco in recent months. Prizes.org, a Slide-backed platform which allows you to create contests for money, like Video Inbox, heavily implements Facebook Connect.
More Info: VideoInbox