Recap: The Cyclopes are the sons of Uranus and Gaia. Uranus imprisoned them in the earth along with their brothers, the Hecatonchires, because he was afraid of their strength. Zeus frees the Cyclopes from prison during the war, and in return they teach him the secrets of thunder and lightning. Fair trade? Well, it worked out okay for Zeus.
Like so many characters in the Theogony, the Cyclopes don't really do much. They're born, they get imprisoned, Zeus frees them, and they hook Zeus up with some awesome lightning bolts. In later versions of the mythology, they also provide Hades with a helmet of invisibility – yep, sort of like Harry Potter's cloak – and they give Poseidon his trident (three pointed spear thing). If you've read the Odyssey then you may remember that Odysseus faces off against a Cyclopes named Polyphemus early in his journey home. Unfortunately, it's not clear if there is any connection between these different Cyclopes. The only thing we really know for sure is that Cyclopes only have one eye. Eek!