@prothero,
To understand 'maya' one may have to take recourse to the following:
If one is a believer in the Creator principle, this concept is easy to understand. The Creator who is the Unborn, gives birth to (Shristi) world. The world comprises of Prakiti (Nature) and Akash (Space or Universe)......... Prakiti is manifest by matter and motion. Both is driven by Prana (Breath of life) or energy. This manifest form is the leela (play or drama) of Bhagavanta (God, the perceived one). Since the unmanifest cannot be perceived, some reports suggests that it can be only be experienced. For the common understanding, it is only that which is perceived as the manifest forms which can be called as the maya.
The understanding of maya has changed with times.
Since we perceive what goes on around us, and this is not permanent in nature, it gives the commoner a belief that the perceived is permanent. The commoner cannot know of the permanent, unmanifest form of reality because of his limitations of comprehension, his conditioning, his environment, his intellect, his traits and tendencies, his habits......... this confines an individual and gives him limited understanding.... this is called the web of maya. Maya therefore does not allow you to reach your pure self or ultimate knowledge or what is known as enlightenment.
The material goals set by self or the society around you is the limiting factor. And this factor is now also referred to as maya.
For an example, an ascetic to be mukt (free) of any bindings or bondings (maya) than he by tradition and scriptural advice has to be a brahmachari (celibate) and only than he can say he is maya mukt (free from maya or free from the artificial, illusory world).
Now, for those who are non-believers, one need to understand 'maya' from the perspective of metaphysics. Since the Universe can be divided into Material and Unmaterial effects, the perceived causes are Maya, as against the real causes. Since we have limited perceivable powers or qualities we mistake what we see or reason for the Real and the truthful.
Secondly, at the lower human level of understanding, the human traits like jealousy, compettition, rivalry, struggle to power, honour, status, even knowledge leading to arrogance and high handedness is due to transitory or illusory notions devloped in our mind. These notions of the material kind can also be called maya. The pursuit for excellence or superiority is an attribute of maya.
Attachments and cravings, passions and desires, avarice and greediness is the result of maya. As long as one is in the grasp of maya - the selfishness of mind, the surrenderance to body, one would be plagued with restlessness, sorrow and suffering. Maya creates anarchy, competition, rivalry, evil, death and destruction.
In the abrahamic world, these attributes are given or represented by Satan or dEvil. The athesits and scientists prefer calling it illusions created by the Ego.
Maya thus imho has two connotations or sub-meanings a) It is the manifest forms of Nature as perceived by man, and b) it is the very natural nature of Man .