Thanks Chris. Just about all the dive sites in Malta are shore dives. With a good guide book (Peter Lemon's A Guide to Shore Diving The Maltese Islands), you can dive most of the sites without a guide as long as you have a buddy. That's what makes Malta so special in my book.
The photographs on the website are from all over the island, each one should have some text indicating the dive site. The ones that require a guide as such are the Blenheim Bomber, Imperial Eagle/Statue of Christ and the filming barge for Popeye. These are boat dives and the guide comes with the boat.
HMS Maori, Um el Faroud (not in photographs), the Rozi are all wrecks that you can dive from the shore. The last two require a bit of a swim and require good navigation skills. A guide is useful for the first dive to these sites so that you learn how to get there and back safely.
The Inland Sea and the Blue Hole in Gozo are also highly recommended dives. Whether you stay on Gozo or Malta, you can dive either as it's just a short ferry trip between the two.