I also like to think of stories of Odin from the point of view of him being a representation of learning, and especially that of learning as gaining through sacrificing a part of yourself (whether that be literal or just time and effort). So for instance:

The change to a snake is representing stepping out of your skin and going beyond the everyday concerns of this life.
Going underground is digging down to the underlying principles.
The female figure down there is sophia (the norns?) - knowledge as a lover.
Sex with her is the striving for enlightenment.
The precious liquid is the gained insights (links to the well).
The giant who changes shape is the past self resisting the change that the insights bring.
The eagle because you must take the knowledge further to escape your past self's limitations.