Controlling Visibility by Role

I have not seen a plugin that does this yet, but to meet my needs I would like to be able to:
a) Create custom user roles. Instead of just Administrator, Editor, Author and Subscriber, I would like to be able to create custom user roles, like family, customer, member, etc. then
b) I would like to be able to specify access and / visibility to posts by category and to specific pages by role.

Doing this would allow me to use the same blog for different purposes with that much more administrative burden.

Is anybody aware of a plugin that would do this?