Hi Moein, you should take a look at these repositories: http://snap.stanford.edu/data/#socnets

http://konect.uni-koblenz.de/networks/

These include various network datasets (e.g. citation graphs), but also plenty of stuff on Facebook, Twitter, Google+ etc.

It depends on your research interests.For example, I have used the data from WoS to investigate authors who collaborate on publishing scientific articles.

Hi Moein, you should take a look at these repositories: http://snap.stanford.edu/data/#socnets

http://konect.uni-koblenz.de/networks/

These include various network datasets (e.g. citation graphs), but also plenty of stuff on Facebook, Twitter, Google+ etc.

All of the above, and:

http://www.cc.gatech.edu/dimacs10/downloads.shtml

https://archive.org/details/oxford-2005-facebook-matrix

All of the above, and:

http://www-personal.umich.edu/~mejn/netdata/

http://www.weizmann.ac.il/mcb/UriAlon/download/collection-complex-networks

http://iv.slis.indiana.edu/db/index.html

This can also be useful:

http://www.autonlab.org/autonweb/17433.html?branch=1&language=2

I also have some data sets (DBLP, email network, co-authorship) that can share with you. The IMDB network database is also very rich.