Adds next and previous links on the resized image when hovering over that half of the image.
This module may be downloaded from the Codex here.
To install, extract the "hover_navigaton" folder from the zip file into your Gallery 3 modules folder. Afterwards log into your Gallery web site as an administrator and activate the module in the Admin -> Modules menu. Once activated you will have an admin option to move the pagination to under the photo.