A challenge for designers is to reach design solutions and to define products that are both new and adapted to the context and to future users or consumers. Indeed, to be competitive, companies have to regularly propose new products to consumers. Moreover, we can consider that there is « something » more than technical knowledge and expertise in design activities : the designers' creativity. We especially argue that non routine design activities are situated on a continuum going from minor creative activities to major creative activities. In line with this view, we first describe examples observed in real-life situations, which show the role of analogies in creative design activities. We also compare cognitive processes described in models of design and in models of creativity. A crucial objective is then pursued : to enhance the emergence of creative ideas from designers. Towards this end, we present experimental results about designers' evocation processes, which suggest how to support professional designers in extending their research space of ideas. Finally, we describe computational systems, whose functioning is derived from such results, and we propose new directions for supporting complementary processes involved in creative design activities.