There is the TANGENT algorithm: http://www.cc.gatech.edu/~zha/CSE8801/CF/p657-onuma.pdf http://www.cc.gatech.edu/~zha/CSE8801/CF/p657-onuma.pdf Applied to a so

There is the TANGENT algorithm: http://www.cc.gatech.edu/~zha/CSE8801/CF/p657-onuma.pdf http://www.cc.gatech.edu/~zha/CSE8801/CF/p657-onuma.pdf Applied to a social graph, it would (hypothetically) find content that is both recommended by friends and probably new to you.