To date, recommendation systems have focused mainly on recommending products to individual rather than groups of people intending to participate in a group activity. In the last decade, with the growth of interactive activities over the internet such as e-commerce services or social virtual spaces, there has appeared many recommendation scenarios that involve groups of inter-related users. Though there have been attempts to establish group recommendation, most of them focus on off-line environments. In this paper we present a novel web-based environment that supports on-line group recommendation scenarios. Specifically, we propose a Collaborative Advisory CHannel for group recommendation called gCOACH. We introduce the environment with the multiple interaction modalities developed to communicate, coordinate and persuade the group in a case-based group recommender. We demonstrate its usability through a live-user case-study.