MyTopo – Online Maps – these are older USGS topo maps overlayed with some such as forest service road numbers. In spite of some maps being outdated, the simple interface makes for a quick reference.
Georgia DOT Maps – Index to county road maps, which are basically the only maps online that actually show the paved or dirt status of all roads outside of national/state forests! Reasonably up to date. Unfortunate interface requires downloading individual county maps one by one.
Trails Off-Road Map – detailed trail guides for individual roads, including photos, videos, reviews. Requires sign-up with email address, facebook, etc. Some features (including to view all trails on the map at the same time) require paid membership.