V.S.
Wow good question. Well I strongly advise no throwing at all. Whether it is at a person or not. I know toddler's get angry, trust me I have a 2 1/2 year old daughter and she throws quite the tantrums. I actually put my daughter in time out if she's really bad. As for how to let them vent anger? My daughter just throws herself on the floor and starts crying. When she does that, she goes upstairs to her room and sits for 5 minutes. Then I go upstairs and ask her if she is done and she says yes and comes downstairs and the attitude is gone.
I guess I just let my toddler throw herself on the floor. That is how she vents anger.