As Peter Kirby mentioned on his blog a few days ago, he has added the Nag Hammadi Gnostic texts to his wonderfully useful website, Early Christian Writings.
Mike Grondin has now added two lists of those materials to his Gospel of Thomas website: one listing the Nag Hammadi texts alphabetically by name, the other listing them by codex. Both lists link to the relevant pages on the Early Christian Writings website.
The Gnostic Society Library also has translations and other useful materials.