Flow monitoring is a scalable technology for providing summaries of network activity. Being deployed at the IP-layer, it uses fixed flow definitions, based on fields of the IP-layer and higher layers. Since several backbone network operators are considering the deployment of (Carrier) Ethernet in their Next-Generation Network, flow monitoring should also evolve in that direction. In order to do flow monitoring at the Ethernet-layer, Ethernet header fields need to be considered in flow definitions. IPFIX provides the flexibility to change the definition of flows, incorporating information from several layers in the network (including non-IP fields). The deployment of IPFIX is still at an early stage, which means that use cases for Ethernet-layer monitoring are not well known yet. This paper provides an overview of the usability of IPFIX at the Ethernet-layer and presents several use cases in which Ethernet-layer flow monitoring provides new insights and different views on a network.