This paper introduces a set of services for the creation of on-line surveys, questionnaires, exams and self-assessment tests within a virtual community system used in e-learning settings. The system, called "Online Communities", is a dynamic web application used as platform for blended learning activities by the Faculty of Economics of the University of Trento. The functionalities added to the platform are contextualized into virtual communities, where activities take place. This allows us to create, submit and analyze questionnaires within and/or outside the boundaries of a community. Furthermore, the system allows to manage libraries of queries organized by the teacher/administrator of the community according to topics and levels of difficulty, in order to produce tests and generate self-assessment sessions on behalf of students. The addition of a questionnaire/poll/self-assessment tool to a virtual community system can add a lot of interesting features, mainly using the inheritance mechanism implemented among different hierarchically-connected communities. This paper will present these functionalities and highlight one of these services, precisely the one dedicated to self-assessment. In the system, self-assessment tests have indeed a double nature: (1) They are useful to students for checking their own level of preparation; and (2) They are useful to lecturers as an indicator of the level of preparation reached by the students. In order to encourage the use of the system within the whole educational process, and not to limit the real use of the service to the period of the final exams only, the possibility has been foreseen for each participant to share his/her own test results, comparing them with the other members of the community, and even offering real "challenges", thus transforming passive and "solitary" learning into something much more stimulating and "social". (Contains 3 figures.)