This paper presents an overview of an opportunity to produce 24/7 global total electron content (TEC) maps using very high frequency (VHF) radio receivers aboard the Global Positioning System (GPS) satellite constellation. Eleven such receivers are currently being used aboard the GPS constellation to detect and locate VHF lightning events across the globe. As a VHF lightning signal propagates from the ground to the satellites, the dispersive effects of the ionosphere and plasmasphere cause the higher frequency components of the signal to arrive at the satellites before the lower frequency components. By measuring the signal time-of-arrival at several frequencies we can derive the TEC between the lightning event and each satellite sensor that detects the event. Using multi-satellite time-difference-of-arrival techniques we can geolocate the lightning and the ionospheric penetration point of the lightning-satellite line-of-sight quite accurately. A single ground station currently provides regional TEC coverage over the western hemisphere. Four well-placed ground stations could eventually provide global, near-real-time TEC measurements to supplement existing systems, especially over broad ocean areas where current ground-based techniques have limited coverage. The paper will describe the measurement technique, discuss some preliminary mapping results and propose a path forward for possible implementation.