I have done things to people that I have realised afterwards were insensitive, and these are the times when I become aware that far from being a firey pit, hell, is a guilty conscience.
The meaning of the word forgive is to let go, or give freedom. Sometimes I think that our greatest mission in life is to forgive ourselves...and perhaps if we did this, we would find out who we truely are...the identity that remains once we let go of our ego.
I am more of a follower of eastern philosophies, but I think that Jesus' sermon on the mount sums this up beautifully when he tells people to look after the planks in their own eyes blinding their vision, before attempting to remove grains of sand from other peoples. I love the imagery of people with planks in their eyes trying to remove grains of sand from others...it conjures the thought of some carry on style movie of a blind surgeon trying to do some heart operation, with the patient waking up to discover...
I think the greatest act of forgiveness is to love.