This paper describes the use of the CoFIND (Collaborative Filter in N Dimensions) system to evaluate two assessment styles. CoFIND is a resource database which organizes itself around its users' needs. Learners enter resources, categorize, then rate them using "qualities," aspects of resources which learners find worthwhile, the n dimensions of CoFIND. Categories and qualities are created by CoFIND's users, so the system sculpts itself to a group's expressed needs. Two uses of CoFIND are contrasted where students added and rated their own Web-based assignments. The first of these provided useful material to help the students with further learning goals, while the second let them use skills they had acquired in a concrete setting. The use of qualities in each instance was very different, reflecting the students' different needs in each case. Based on these results, suggestions are made as to how virtual ecologies of self-organising groups of learners might be encouraged to thrive and grow.