Wow! Things have changed! I started this thread when we had our first pullets back in 2009. Was very surprised to see it pop to the top of the thread list this morning.
As a follow-up: I gave up on figuring out who is laying what egg. If I happen to see a hen leave a nest box and there's one warm egg inside and it's the right color for her, I'll write it down (they're all leg-banded with numbers). Otherwise, I'm sure that there are some freeloaders out there. But with 35-45 eggs/day, there's still no good way for me to figure things out.