As expectations for the Internet to support multimedia applications grow, new services need to be deployed. One of them is the group communication service for one-to-many or many-to-many data delivery. After more than a decade of important research and development efforts, the deployment of multicast routing in the Internet is far behind expectations. Therefore, a first motivation for an alternative group communication service is to bypass the lack of native IP multicast routing. Although less efficient and scalable than native multicast routing, such alternative services are generally suitable for the purpose. A second possible motivation is to go beyond the limitations of classic multicast routing for very specific working environments. We identify, classify, and discuss some of these alternative approaches.