Hi Shelbel
DS is 3.8 and went through a very agressive stage (for him) about 2-3 months ago. Up until then he had never hit, or even thrown toys about much, alhtough he did have tantrums when he was younger - I mean just thrashing about on the floor and screaming, but not being outwardly aggressive.
I absolutely agree with bluestocking about not making a big deal out of the behaviour you don;t like.
My approach is usually (unless I am very wound up!) to say firmly something along the lines of "I can see xxx is making you angry but we are not doing yyyy". I then try & leave him to it and ignore any wild outbursts.
If he tries to hit or scratch me (or even bite, which he tried once) I ask him to stop and think about what he's doing, always make sure I back it up by reminding him that he musnt hit and why.
Sometimes I say to him "look, if you are feeling really cross, do this" and run into the living room and start punching a cushion, which usually breaks the tension unless he's too far down the line.
DS really only behaves like this when he is tired and I agree also about wind down and perhaps limiting tv a bit more. Counting down to bedtime and reminding him about what is happening next is really important for DS, as is his bedtime routine, especially during the week when he is more tired.
I don;t use the naughty step but sometimes ask DS to go into the hall and sit on the stairs to calm down if he is really raging.
He seems to have calmed down a lot again recently so there is hope