The only place I feel weird of not following ppl back is tumblr.
Well, taking 4 example LJ, I don't even remember 90% of ppl I friended back in time (10% are my RL friends), I don't even check my flist there, and the ones who are not friends of mine, I don't even want to check who they are. Sometimes, I wonder though why I'm still in their flist.
I guess they wanna keep track of my writing as it is mostly the only thing I post there.
But when it comes to tumblr, all my followers seem like such sweethearts (maybe it has to do smth with them being young and not bitchy) and I feel like a cold heartless bitch of not following them back *sighs*