The act of adding someone you don't know on MySpace or Friendster because you feel bad for them and don't want to be mean.
"I have no clue who that guy is, he was a pity add."
The process of, out of pity, adding as your friend on MySpace or Friendster or Facebook (etc), a person that is not exactly your friend. Usually it is the pitied person that initiates the process, so all the other person needs to do is click 'confirm' or 'yes'.
Girl 1: I keep clicking ignore but Erin keeps trying to add me on Facebook!
Girl 2: Ugh, I know! But I finally decided to pity add her..
Girl 1: But why??
Girl 2: Well, cuz her parents are divorcing & Ann says Erin's suicidal & I don't want my name in that suicide note.
Girl 1: Ooohhh.. *clicks confirm*