Ah, I see there are some nits to pick!
First of all, I shouldn't have to say this: Nazgul_Lord and Anarchist, it's
Maiar for PLURAL, and
Maia for SINGULAR! Sheesh.

And yes, it's spelt 'invisible', not 'invisable'.
The nitpicker has left the building.
Grond I think those are some pretty insightful ideas. I have read somewhere that both
Elves and Maiar live in the Seen and Unseen worlds at the same time. And as
Sauron was a very powerful Maia, he did too. And
Tom.. well, just don't blow a fuse trying to figure that one out.
If the wielder is already half-invisible (in a sense, not some freakish floating figure),
the Ring does not make him invisible. But
creatures like
Men,
Hobbits and..
Gollum are 100% in the Seen world, and therefore they do turn invisible. I'm not sure about Elves, though. I don't think an
Elf has ever worn
the One Ring..