The farmer's daughter was an illusory character created by the Caretaker. She was part of an illusionary farm scenario, created to make the crew of USS Voyager feel at ease. She greeted Paris and made amorous advances. When Kim and Paris detected a lifeform in the barn, she tried to stop them from entering. She turned violent as did the rest of the illusionary people, telling Paris that she was not ready for them. She punched Paris knocking him to the ground. (VOY: "Caretaker")
These two holographic harps were a program that William T. Riker was listening to when he was called to the transporter room when a Betazoid gift box from Steven and Victoria Miller as a wedding gift for Deanna Troi was beamed onto the ship. (TNG: "Haven")
The Minosian peddler was an automated sales-pitchman for the Minosian Arms Industry of the planet Minos, who were noted for technologically advanced weaponry, an example of which was the Echo Papa 607. The salesman promised good deals and promised peace through superior firepower.
At first the USS Enterprise-D crew believed him to be real. They soon realized that it was a pre-recorded holographic message, and that the Minosian civilization had been wiped out by their own weapons. (TNG: "The Arsenal of Freedom")
Qomar singing holographic matrix
The hologram shared the same appearance of The Doctor, with the difference of looking like a Qomar, instead of a Human. It was designed to sing far more complex musical compositions than The Doctor was capable of. Specifically it was designed to extend the range of humanoid vocal capabilities. (VOY: "Virtuoso")