This may have already been mentioned here, but I just came upon this book and have found it very clear and to the point. It contains a number of wonderful pointers to the "I Am". It is a collection of 231 quotes, with a short commentary that follows, taken from Sri Nisargadatta Maharaj. A free download is available here:
http://www.holybooks.com/nisargadatta-gita-pradeep-apte/
I hope you find it helpful.
Metta,
Brian.
The first quote and commentary:
1. The ‘I am’ came first, it’s ever present, ever available, refuse all thoughts except
‘I am’, stay there.
Understanding the ‘I am’, your sense of ‘being’ or just ‘presence’ is extremely important
as on it rests the entire outcome of the teaching. Firstly, are you at all aware of your
‘being’ or of the fact that ‘you are’? You have ‘to be’ before anything else can be,
your sense of ‘presence’ or the feeling ‘I am’ is really fundamental to anything that has to
follow. Secondly, this sense of ‘being’ or the feeling ‘I am’, was it not the very first event
or happening before any of your living experiences could begin? Apply your mind go
back in time to the moment when it dawned on you that ‘you are’ or ‘I am’. This ‘I am’
is still there with you, everpresent, ever available, it was and still is the first thought,
refuse all other thoughts and come back there and stay there. So try to understand and
grasp this ‘beingness’ or ‘I amness’ that is inherent in you. The more precisely
and clearly you do it the more rapid will be your progress.