Alanna Smith became a virtual assistant after quitting her job as a communications officer. She's earned about $4,000 a month in revenue through her virtual-assistant business Ask Alanna.

Mercedes says its virtual assistant transforms the "car-driver relationship." The artificially intelligent computer KITT from "Knight Rider" could do it all -- drive solo, speak to humans, land ...

The choice between an AI system and a human virtual assistant will ultimately depend on the specific needs and goals of your business.