Biomedical ontologies such as the 11th revision of the International Classification of Diseases and others are increasingly produced with the help of collaborative ontology engineering platforms that facilitate cooperation and coordination among a large number of users and contributors. While collaborative approaches to engineering bio- medical ontologies can be expected to yield a number of advantages, such as increased participation and coverage, they come with a number of novel challenges and risks. For example, they might suffer from low participation, lack of coordination, lack of control or other related problems that are neither well understood nor addressed by the current state of research. In this paper, we aim to tackle some of these problems by exploring techniques for recommending concepts to experts on collaborative ontology engineering platforms. In detail, this paper will (i) discuss different recommendation techniques from the literature (ii) map and apply these categories to the domain of collaboratively engineered biomedical ontologies and (iii) present prototypical implementations of selected recommendation techniques as a proof-of-concept.