Many of our modern computerized activities, may they be personal, industrial or artistic, involve searching, classifying and browsing large numbers of digital objects. The tools we have at hand, however, are poorly adapted as they are often too formal: we illustrate this matter in the first section of this article, with the example of multimedia collections. We then propose a software tool for dealing with digital collections in a less formal manner. Finally, we see that our software design is strongly backed up by both artistic and psychological knowledge concerning the ancient human activity of collecting, which we will see can be described as a metaphor for categorization in which two irreducible cognitive modes are at play: aspectual similarity and spatio-temporal proximity. ReCollection, the software we have designed to experiment and demonstrate these ideas may be useful in many areas of musical creation, from sound synthesis to archiving, editing and publishing content, and also simulating musical perception.