I would only know about STT and that's a great question. I've never seen one at all and I'm wondering why?

There's one on Buck Island off the south shore of St. Thomas. Some of the other islands or cays off St. Thomas's shore might also have light houses, but I'm definitely aware of this one.

Gerie,
You are right on, I don't know of any others.

St. Thomas Lighthouse
Buck Island (1)
1913. Inactive since the mid 1990s. 25 ft (8 m) square steel tower with lantern and gallery, attached to a small service room. The lighthouse was painted white and the lantern black, although nearly all the paint has weathered off the building. The Coast Guard has a historic photo, and a 2007 photo and another recent photo are available. The active light is on a square cylindrical steel skeletal tower (focal plane 339 ft (103 m); white flash every 4 s). This lighthouse was built by the Danish government shortly before the islands became a U.S. territory in 1917. Clearly endangered, the lighthouse was added to the Lighthouse Digest Doomsday List in April 2004. Located at the highest point of Buck Island, about 3 mi (5 km) south of St. Thomas. The island has been a wildlife refuge since 1969. Accessible only by boat. Site open, tower closed. Owner: U.S. Fish and Wildlife Service. Site manager: Buck Island National Wildlife Refuge. ARLHS VIR-002; Admiralty J5628; USCG 3-33060; NGA 14632.