Control access to parts of a system, but also to certain pieces of information
Add additional column "category" or "type" to the table(s), that will categorize the rows (or if you will, group/cluster them) - and then create a pivot table that defines the access control between (rowCategory, userGroup). So for each row, by its category you can pull which userGroups have access (and what kind of access).
This is a tricky question, we've been talking about this for a while (days) and haven't found a convincingly good solution. This is the situation:

We have users and groups. A user can belong to many groups (many to many relation)
There are certain parts of the site that need access control, but:
There are certain ROWS of certain tables that need access control, ie. a certain user (or certain group) should not be able to delete a certain row, but other rows of the same table could have a different permission setting for that user (or group)

Is there an easy way to acomplish this? Are we missing something?
We need to implement this in python (if that's any help).