As far as I'm concerned, of the places I have dove, Grand Cayman has the second best shore diving behind Bonaire. There are a number of relatively shallow sites all around down town George Town and well as some mini walls up on the north end of the island. And unlike everything else on the island, tank and weight rental are fairly cheap. Don Foster's charges $8 US per tank for the wreck of the Cali and Eden Rock charges comparable ($10 per tank - nitrox) for Eden Rock/Devils Grotto.
Of the places that I've been to but haven't dove or done shore dives, I hear Curacao is very similar to Bonaire. We went there on a day trip from Bonaire, but didn't do any diving.
Also, Maui is supposed to have a number of good shore dive sites. We only snorkeled from shore and it was really nice and you can dive Molokini crater (this is a boat dive, but well worth the ride) I plan on going back there this January to specifically check out the shore diving.
