00 Bumerang António José Videira Tavares Polytechnic Institute of Cávado and Ave, Portugal INTRODUCTION The peer-to-peer (p2p) systems have promising char- acteristics to the sharing of digital resources--digital contents, processing power, bandwidth, and storage--in a free and equal way, among the members in a com- munity of equals (peers) (Androutsellis-Theotokis & Spinellis, 2004; Barkai, 2001; Fattah, 2002; Milojicic et al., 2002; Oram, 2001; Schoder, Fischbach, & Schmitt, 2005). A member of a community could decide when and what he wants to share, knowing that to obtain something of his interest, he should offer something in return, and that the success of his community depends in some way on his own contribution and participation. This property is very interesting in academic environ- ments and very reaching and diversified in collabora- tion forms, expression ways, and formal or informal resources (Loo, 2003) with SETI@home (http://setia- thome.ssl.berkeley.edu/), the most notable example of a system based on the aggregation of computational resources with no costs, reeling in the persons willing- ness to contribute to a project nonprofitable project and helpful to the humanity. In the academies, if in the beginning p2p applications were only seen in this entertainment component and therefore responsible for a huge waste of computational and bandwidth resources, presently, a strong interest and curiosity in academic environments is rising (Berman & Annexstein, 2003; Oram, 2001; Schoder & Fischbach, 2003) with lots of potential applications, for example, transmitting huge amounts of data, large processing power with ad-hoc grid computing, streaming, and others. Projects like Edutella (Nejdl, Nilsson, Wolf, Qu, Decker, & Sintek, 2002), Comtella (Vassileva, 2004),