...always forgive your enemies..nothing annoys them so much.
--- Oscar Wilde
So much can be said about that quote. How true is it though? Really, why bother to hold anger, resentment against someone else. They don't care. You are only hurting yourself. Easier said then done sometimes, but it really is the best way. Let it go. Besides when you can let it go and they do notice that (and they will notice) they will be annoyed! ;)
Who are you mad at?
Who do you dislike right now?
Let it all out...