I used to use topozone, but now that trails.com has purchased them it is fee based. Someone from another forum I frequent was also distraught over the loss of topozone, so he coded his own replacement. http://adirondack-park.net/topo/
It seems to be even better than topozone since it has multiple layers. The focus is obviously on the adirondacks, but the map is for all of the US.