With all the time traveling and unforseen meetings, I thought it would be interesting to see exactly who knows who. No real theory here, just foor for thought:

Daniel and Danielle have never met
Daniel and Ben have never met
Daniel and Hurley have never met
Miles and Jin have never met
Miles and Desmond have never met

Desmond and Ben have only been in the same place at the same time once (briefly)
Locke, Jack, and Sayid have met pretty much everybody

I found it odd that Ana Lucia would appear to Hurley, considering the two never had a big scene together, if at all.

What's worse, though, is that Hurley's mother apparently didn't recognize Sayid, even though she had met him twice.