Google Helpouts is a service that uses Hangouts to get users with questions in touch with experts. Categories include Computers & Electronics, Education & Careers, Fashion, Fitness and Music, among others. You use your Google account to sign in, and the interface is plain but intuitive.
Most Helpouts are free, but the experts can set a fee for their services. Once finished, you're able to rate your experience so that others can get an idea of the service they should expect.
It's an interesting concept, but so far has seen limited success. Maybe opening up the process to iOS users will make a difference here.