I apologise for the lascivious food-talk that will follow:
Mine is always bread. In all its glorious forms - naan, pitta, white, brown, croissant, brioche, toasted, warmed. Sometimes the bread craving comes with an accompaniment such as baked beans or curry but the bread part seems to remain constant...
Bizarrely, before LL I didn't really eat a lot of bread (although, clearly, my idea of 'not a lot' was fairly skewed) and never craved it.
I read on another thread that Atkins says that you often crave things that your body is intolerant to, but who knows...