That's true, we have to be very careful what human foods we let kitties taste. Here is a list of other foods that are no-nos: http://www.cat-world.com.au/cat-worldtoxic.htm
(at the bottom, under the toxic and non-toxic plants).
Anything with essential or aromatherapy oils in them should not be in the same house with a cat, even if you don't think it is touching them.
But, yes, it is normal for cats to want our food. It's more interesting than theirs and it's what we're eating, of course! Zissou loves... everything except peanuts.