Presumably you have business logic that relates to how you process data in the DB. That data is likely to be table based and the tables are likely to be per business entity.
For example, there might be a table that holds details of customer accounts. Therefore all business logic pertaining to creating, maintaining, validating, listing, etc. of customer accounts would exist in the package PKG_ACCOUNTS.
Without knowing how granular or generic your procedures are trying to be its hard to see how you would need something more that that. That sort of approach, with packages covering logic that can apply to multiple objects, has always worked very well for me.
Perhaps some examples would help if you don't see that this is sufficient.