Our online map viewer is now  to the point where you can link to a set of layers, along with the center and zoom of the map.

For example, here you can see MapBox Cloudless Aerial imagery, overlaid with GMUs, WMAs, and public land ownership. This is a good combination for hunters, and you can achieve the same layered effect, offline in the woods, with Gaia GPS for iOS. Or perhaps you would like to overlay US Forest Service Maps over the more broad coverage of the USGS maps – this is a very typical combination for me hiking around Tahoe.

Like Gaia GPS, this web viewer already brings together a really useful and diverse array of maps from CalTopo, MapBox, and ThunderForest. We are also doing a lot with Leaflet and TileMill now, to expand map coverage, and the tools you can use online with these maps.