Prisons in the US do very little to rehabilitate people into becoming active members of society.
By providing online educational resources even as simple as Coursera or Kahn Academy, and allowing people to maintain social connections through Facebook, not only would it give inmates a sense of community, but it would also allow them to finish their sentences with advanced degrees. A sense of community is crucial so that they do not feel isolated, as that makes them more likely to commit a crime again.
Furthermore it would serve to create a layer of transparency that is lacking in many prisons and would allow for more independent scrutiny of human rights issues.
Inmates should receive at least 4 hours/day of unrestricted internet access in a private setting.