Pinterest is great! I saw a link for making a time out jar there. This is basically just a jar with glitter, glitter glue and water. Glue the lid on and shake it up. The glitter floats around and then settles again but swirls around while on the way down. The great thing about this is that it fascinates children and is hypnotic creating a great way to calm the mind.
I happen to try and use Positive Discipline which tries to find ways to help a child feel better rather than worse when they are getting into trouble. The idea is that there is something they are trying to show they need through their behavior and so if you can figure that out and calm them down in a positive way you can have a conversation they will hear rather than block.
I think that teaching my children how to find strategies to calm down when angry in a way that will end up with them feeling better about themselves and happy is a win. I think that this fits with that idea well. Another thing to put in the calm down area (time out area with a positive discipline twist).
We have used this cool down jar with great success so far. When my son is getting excited about something in particular. For some reason that seems the most difficult thing for the two of us to deal with together and get him to settle down. This has worked very well in helping him calm down. We even made one that is in a plastic tube (the one the glitter came in) that we can take with us.
One thing I did is put a permanent glue around the threads of the jar lid so that it will not come off.