We all know the Webcam in Cruz Bay, keeping watch, 24/7, over the ferry dock. It's not unheard of for people to write their names on the beach and then call friends by cell phone and say, "Look, Ma. We're here." That's what "mbw1024" "Xislandgirl" did.
Now there are two more Webcams on St. John, apparently being hosted by someone for the Virgin Islands Daily News. Both are on the east end. One is aimed at Coral Bay. The other is looking around the corner at Hurricane Hole.
And if you want to check to see whether the weather 
on St. John's the same as on St. Thomas, there are three Webcams across the sound.
One's at Mountaintop, Home of the World famous Banana Daiquiri. The other two are at sea level. One shows Havensight where big cruise ships dock, and the other (pictured at left) is watching the new luxury condo/retail/restaurant/marina development, Yacht Haven Grande. (The big yacht, about 130' that is docked there, is captained by my brother in law, Kirk Thieme.