If many-to-many association is to be implemented (request 1315), it would be really helpfull to have a class representing that many-to-many association.
If a class could represent this association, then additional values for the association/link would be possible, like for example a user confirms attendance to a course. Confirmation for the above is only relevant if a association actually exist.
N.B: This type of association was implemented in Bold/ECO, and I found it very usefull and would simplify the the model considerably.