In one of the posts re: Jacob's identity someone mentioned that in the Bible, Aaron is the great-grandson of Jacob. I'm not a Biblical scholar by any means, but if that is true, then I'll subscribe to the theory of Ray Shephard (Jack's grandfather) being Jacob and our Aaron is his great-grandson.
When we first meet Ray, he's "escaped" again from the elderly residence. The whole "what would I do without watching magic acts" is a coy cover for the fact that he leaves the elderly residence to travel somehow to the Island.
Perhaps the cabin that Horace builds is to keep Jacob (Ray) contained and not have free reign through time and space via the Island. The reason that Christian and Claire are in the cabin is that they are family (his son and granddaughter). When Jacob says "Help Me" to Locke, it is his way of asking Locke to help Jack discover his true purpose and destiny. It isn't an accident that Ray has his deceased son's shoes.
I know I'm not the first one to suggest the Ray is Jacob theory, but I'd be curious if others still subscribe to this possibility. Are there other clues supporting this theory?