There are the Pyrgi tablets, which contain a bilingual text in Etruscan and Phoenician (which is a close relative of Hebrew and Arabic, and so easily readable). The Emperor Claudius wrote an Etruscan-Latin dictionary, but that has been lost.

A propos of the Rosetta Stone, Ancient Egyptian also benefitted from having a direct descendent language (Coptic), spoken until a few hundred years ago and still used in Coptic churches. Etruscan has no modern descendants.

We do have a partial knowledge of Etruscan though, so it isn't quite a closed book the way Linear A (Minoan) is. See http://www.etruskisch.de/pgs/vc.htm