Ian links to this post on periochoresis- the idea that God dances together in Trinity.
The article is a good read.

I wrote an essay on this around a year ago and remember being struck by the idea of God creating out of this Trinitarian Dance – a dance where each part of the Trinity moves in intimate relation to each other. I was struck by the thought that God exists in relationship. That may be obvious to you, but I had not really thought about it. Yes I knew all about the 3 parts of the Trinity, but I guess I had compartmentalised and seperated them.

I concluded that as God lives and creates out of this dynamic relationship, that we, as humans, need to be dancing in dynamic relationship with God and others (a secondary trinity of God, me and you?)to live and create as well.