Mobile phones are becoming a primary platform for information access and when coupled with recommender system technologies they can become key tools for mobile users both for leisure and business applications. Recommendation techniques can increase the usability of mobile systems, providing personalized and more focused content, hence limiting the negative effects of information overload. In this article we review the major issues and opportunities that the mobile scenario opens to the application of recommender systems especially in the area of travel and tourism. We overview major techniques that have been proposed in the last years and illustrate the respective supported functions. We also illustrate specific computational models that have been proposed for mobile recommender systems, and we close the article by presenting some possible future developments and extension in this area.