In 2007, God was the most wanted person on Google, and this search for God is on a slightly increasing curve. I'm not sure how I should read that. The immediate reaction is that more people are getting religious. At the same time, it could be an indiction of the opposite.
Who God is, is described fairly well in the Bible. First book. First chapter. First sentence. "In the beginning God created the heavens and the earth." I believe this to be a fairly well known fact. And that as far as we can define God within the limitation of our heaven/earth view.
After all, if God created our physical world from within a non-physical world, then God's existance is beyond the world we are able to see and comprihend. And as our understanding of abstract ideas also is limited by our physical comprehention, it is also reasonable to claim that God is beyond our abstract understanding as well.
By asking who is God, we place God and attempt to define God within our limited earthly understanding of persona. The question can not be answered under those terms. Similarly, if a TV screen could think, he would ask "What colour is Obama's eyes?" and see this as the very definition of Obama.
Hence, the best a human being can do is not to define God within our earthly ways, but to experience and appreciate. To do this, you have to stop asking "who" and start paying attention to your senses instead.