Aggregation operators have been used and studied for a long time. More than ten different types of means (including the arithmetic, geometric, and harmonic ones) were already studied 2000 years ago. Nevertheless, this topic has gained relevance in recent years. This is partly due to the increasing need of methods and operators for fusing information within computer programs. In this paper, we will present a personal view of the field, focusing on the application issues and on averaging aggregation operators. We will point out some research topics and open lines for future research. © 2007 IEEE. This work was supported in part by Generalitat de Catalunya (AGAUR, 2004XT 00004) and by the Spanish MEC (projects CONSOLIDER INGENIO 2010 CSD2007-00004 and e-AEGIS TSI2007-65406-C03-02). Peer Reviewed