Archaeologists found a pottery shard with something like Goliath's name on it.
Digging at the town of Tel es-Safi, possibly the ancient Philistine town of Gath, they found this shard and it dates to about 950B.C. Addendum, since Petrie started excavating in the Levant, it has been pottery styles that have been used as references to date the age of unearthed strata.
Lets navigate a possible path between the literalists who hold the Bible as totally true and those who dismiss the Bible as self-aggrandizing writings of some nomadic tribes to look at this pot-shard. Since Goliath might have been a common name of that era, it offers possibilities. Goliath did not have to be a physical giant, just a very good soldier who happened to be named Goliath. And David managed to slay him, hence causing consternation in the Philistine host.
It would still be a tremendous victory for the Israelites that like good stories did 'grow' a bit in the retelling. And possibly another piece of evidence backing up the Bible's telling of events.