Other Greco-Roman Oracles
Oraculum, from Charles Smith, Dictionary of Greek and Roman Antiquities (1867), pp. 836ff. A very comprehensive run-down of all oracles mentioned in Greek and Laitn literature. Exhaustive, if out of date.
Oracle from Oskar Seyffert's Dictionary of Classical Antiquities (1894). Three pages.
Oracle of Zeus Ammon at Siwa
Pothos.org: Divinity and Siwah by Nick Welman. Pothos is my favorite Alexander site not run by me.
Tour Egypt: Siwa. Excellent introduction, particularly for a tour site.
They also have a nice essay, The Oracle in Ancient Egypt by Marie Parsons.
Siwa: Oasis Extraordinary by Torben B. Larsen, Saudi Aramco World (September/October 1988)
Abstract: "The Oracle and Cult of Ares in Asia Minor" by Matthew Gonzales, APA 2004.
Abstract: "The Gods and Oracles of Ancient Lycia" by Trevor Bryce (for a 1993 conference in Australia). Bryce is the world's leading expert on the seam between the Hittites and Luwians and their Anatolian descendants, the Lycians. This abstract (down the page), indicates it is likely that some of the Greco-Roman oracles in Lycia "had their roots in oracular traditions extending back at least to the 2nd millennium BC."