Answer to last puzzle, as given by D4 (and others):
Fill up the 5L jug and pour it into the 9L jug, pour into the 5L jug again, pour as much possible into the 9L jug. You'll have 1L left on the 5L jug, empty the 9L jug, pour the 5L jug into the 9L and then another full 5L. Leaving you with 6L in the 9L jug.
It's an interesting puzzle because there's so many variations on it simply by changing the volume of the jugs, the final amount of water required, adding more jugs, etc etc... An interesting subquestion is, Given two jugs of defined volume, what exact quantities can be measured from them? Or given a quantity, what two jug volumes can be used to measure it? If not two, what about three?
A New York city hairdresser recently said that he would rather cut the hair of three Canadians than one New Yorker. Why?