The magnetic fields detected by the Pioneer Venus Orbiter (PVO) magnetometer within the electron density depletions called ''holes'' in the nightside ionosphere are typically larger and more organized than the fields in the surrounding ionosphere. Moreover, they have substantial sunward/antisunward components which cause them to appear as near-radial fields near the antisolar point. The collection of observations presented here illustrates the variety of appearances of the fields in holes. Some new results which summarize their average properties, their dependence on solar wind conditions, and their lack of geographical control are also presented. These results are potentially pertinent to the interpretation of data from the PVO entry at the end of 1992 and from the impending Mars Observer mission, which will probe the magnetic fields in the low-altitude wake of weakly magnetized Mars.