I see a counselor once a week. SHe's an addiction specialist, but helps me in any area of my life that I share with her. It's a good safe place to vent, and she can give me a perspective on my problems/situations that I don't have myself. I"d be lost without my sessions with her. I trust her with my life and she's done me a world of good.
Another thing I do when I get frustrated is post on Whiner's Anonymous! Just venting what's bothering me helps to 'let it go'.