.Being a cynic I am inclined to say that the vast majority of what is termed magic is due to a disparity in skill or technology... certainly I think this is why the Elves were bemused by Sam's question.
I remember my grandmother telling me how her father was amazed when he heard a live radio broadcast - the child of someone in the village was playing at the Albert Hall - and that they in a village in Gloucestershire could hear something as it occured in London was pretty much magic to him. Even for me as someone who was born into a world where we were impressed by digitalwatches and simple calculators it is mind boggling the diffence in technology - I never expected at the time I first read the Silmarillion that I would be discussing it twenty odd years later with peple all over the world on my own "palantir" ...
However at times there is clearly more going on and there are some threads already where this has been looked at already (but not especially recently).
http://forum.barrowdowns.com/showthread.php?t=11261
This is one - not necessarily the best but one I can find easily because I started it...