On a.m. Page I found dead Link for "Donate" to <http://challenge.documentfoundation.org/> behind Κάνε δωρεά χρημάτων για την χρηματοδότηση του project: Should lead to <http://www.libreoffice.org/get-involved/donate/>
that's true go to http://el.libreoffice.org/get-involved/ localize this text link: "Κάνε δωρεά χρημάτων για την χρηματοδότηση του project:" it points to a dead link: http://challenge.documentfoundation.org/ instead of http://www.libreoffice.org/get-involved/donate/
Fixed, but only partially - there seems to be no Greek translation for the donate page, so linking to English one