The One Ring?

[Marileangorifurnimaluim]

Any interpretation is valid from a personal point of view, including cockamamy marriage theories (thank you *tree for writing Exactly what I was eagerly composing in my mind, even my examples!). It's just not Tolkien's intention. Iamarquise is right (welcome, by-the-way), Tolkien intended to portray fundamental truths of human nature. The one ring is a handy means to explore the the nature of evil, corruption, it's seductiveness, how even good intentions can lead down that path. There's a difference between symbolism, allegory, and a thing used to explore truths.
Allegory points out a particular moral, preaches. Symbolism uses an item to mean something other than itself, so the "thing" becomes overwhelmingly important. Using a thing to explore and reveal truths is this close to Allegory, but you are left to draw your own conclusion(s). Thus the meaning of the one ring is subtle and multi-faceted. Just like the nature of evil.