[Verginius Rufus]

There are various mentions in Greek sources of the Pelasgians but they are rather mysterious. One scholar tried to equate them with the Philistines but I don't think anyone else agreed with him. Their language may be related to Etruscan. The island of Lemnos had a non-Greek-speaking population until fairly late when it was conquered by the Athenians and a couple of inscriptions have been found there in a language similar to Etruscan (but written in the Greek alphabet).

A lot of place names in Greece are pre-Greek: Athens, Corinth, Knossos, Parnassos, etc. There are also many loan words in Greek which seem to come from the same language. One of them is plinthos, "brick," which may indicate that the Greeks learned how to build with bricks from the earlier population.

[SunkenCiv]

The -inthos endings means "place of", and appears in Corinth (the Place of the Carians) and is found scattered around the Mediterranean. As VR said, there's a longish inscription on Lemnos (not surprisingly, called the Lemnian Stele, and FR has a keyword for that) that appears to be in a language related to Etruscan, or actually is a dialect of Etruscan.