The deployment of IP Network Address Translators (NATs) for IPv4 has become very pervasive in the last 10-12 years. The original goal of NAT was to conserve IP address space, but the technology has now become very popular in home and SOHO type networks, as well as many larger organisations, for a variety of reasons. At the same time, the introduction of NAT adds a cost for application and service developers. This document presents a brief overview of the history of NAT, alongside a list of ongoing work related to NAT workarounds for current IETF protocol designs. The document intends to present a neutral view of the cost of NAT for discussion in the IETF and wider community.