I think it can be pretty much anything you want! I plan on bringing something that is from Idaho, but on the fish extender subjects I have read people bring anything from temporary tattoos, candy, pens or pencils, to
little treasure chests with little toys in them, homemade bookmarks, magnets, etc.
I imagine we will be keeping track of kids too, so that we can give something appropriate for the kids that might be different than the adults...
My boys were reading one of the fish extender subjects and got some fun ideas for making our own... but first I need to either FIND my iron or buy a new one! Packed it 4 yrs ago and havn't seen it since...
And yes, you bring with you to the ship... you can drop them off during the week in each family's fish extender that will be hanging next to their stateroom door! It is fun to have little surprises show up during the week...