Restrict plugins by user role

A lot of focus on customising user roles seems to be on which categories or posts are viewable, and what administrative privileges are available. I’m looking at something entirely different.

I want to be able to offer a premium membership (paid) to my readers which gives them additional features on my blog beyond being able to create/edit posts that the current role manager allows. I’d really like to offer additional stuff to these members so it would be great if there is any way of limiting certain plugins to a particular role, such things as comment karma restricted to certain users, or flagging new posts, even something like providing an event calendar to premium subscribers that’s not available to other roles.

In theory this is sound as it should be managed the same way admin privileges are granted to a particular role, but i have no idea about how i’d write it, or if anyone has tried taking this kind of thing on.

Would appreciate if anyone could help point me in the right direction.

Thanks