Repositories of learning objects are increasingly becoming available on the Internet. The quality of the learning objects that they store as well as the mechanisms provided to easily find them for reusing are very important. Learning Objects Board (LOB), built around the ?stock exchange? metaphor, brings a new concept of Learning Objects Repositories pushing users motivation to produce good learning objects as well as increasing the cooperation between users either by submitting suggestions, comments or rating existing learning objects. To achieve such high level of motivation and interest some kind of healthy competition is promoted, assigning credits to users and setting a value cost for each learning object. This credit-based system allows the creation of users and learning objects rankings, and consequently permits reward those users that collaborate by creating LO or by adding valuable information to the existing LO, and increases the value of the most popular LO. This paper presents the major results from the design experiences that have been developed during the LOB implementation phase. Finally, the paper discusses some open issues and future work.