TeachStreet, a Yelp-like service for real world classes (cooking, dog obedience, music lessons, ballroom dance, foreign language, golf, yoga, etc.), is launching a marketplace feature for teachers to be able to coordinate payments from students. TeachStreet, which serves seven metropolitan areas in the U.S. including New York City, Silicon Valley/San Francisco and Seattle, allows instructors to upload information about classes. Users can look for available classes, and read and write reviews on the course and the instructor. Currently, the site includes a selection of more than 135,000 classes and teachers, across more than 700 subjects and categories.