Methods and apparatus for emerging use case support in user space networking architectures. In one embodiment, an apparatus configured to segregate packet data based on a packet type is disclosed. The exemplary embodiment provides a custom data type registry that enables the definition, addition, removal, modification, and/or prioritization of custom packet processing rules. Variants of the registry may support custom ethertype packets, network packets, and/or transport packets. In another embodiment, mechanisms for enabling an intermediary packet processing stage are described. Intermediary packet processing may enable user space system extensions that support e.g., packet filtering, packet modification, and/or other forms of packet processing.