This is very out there, but I just thought "What the hey-hey".

Look at the shape of the numbers. Does 4 resemble a sitting figure with arms down (Locke pushing a wheelchair), 8 may represent Hurley himself, 15 kind of resemble the trigger of a gun.

All reasons they ended up on the island (Hurley being the numbers themselves). Of course I have no idea what 16, 23, 42 and 51 could be so my theory falls flat right there!

Ain't pondering grand!