Implementation of automated volume-to-volume registration applications for three separate registration steps desired in enhancing neurosurgical navigation is considered. Prototype implementations for MRI-to-MRI registration, MRI-to-US registration and US-to-US registration have been made using registration methods available in the Insight Toolkit, with variants of the Mutual Information similarity metric. The obtained results indicate that automatic volume-to-volume registration using Normalized Mutual Information should be feasible for the neuronavigational applications considered here, with sufficient accuracy.