I would love to have the possibility to assign webpages on a individual level in addition to Roles.

For example:
Think about website that deliveres a e-learning environment to Trainers and Participants.
For each participant I'd have a Personal Page, that provides the possibility to drop assignments (home-work) by participants.
So when 5 participants join a training, for each of them I'd create a personal page, only viewable by the individual. Besides that, the tailor-made Role "Trainer" would be given access to view all the 5 personal pages of the individual participants...