Next Google, Facebook, Twitter? 5 Possibilities

Who will be the next

Google(1998) -Search, Facebook(2004) - Social Networking, Twitter(2006) - Microblog

and the next category creators on the internet.

Here are the 5 possibilities based on my understanding:

1. Zygna (2007) - Social Gaming (Mark Pincus)
2. Groupon (2008) - Collective Buying (Andrew Mason)
3. FourSquare (2009) - Location Based Social Networking (Dennis Crowley)
4. Square (2010) - Mobile Payment service (Jack Dorsey - also, Twitter founder)
5. Layar (2010) - Augmented Reality Apps (Raimo)

Other companies who came close are Obopay, Spotify, GetJar, Bump, Flipboard

Do you have any recommendation?