USGS Topo maps layer for Google Earth

I spent this morning flying around Northern Colorado looking for a place to swim in the Poudre River near Fort Collins (any ideas??) - I then had a need to add a USGS topo layer to my Google Earth session - enter good old Frank Taylor (aka. Google Earth Blog founder) and a solution! A great add-on for Google Earth from a company called 3D solar was found, enabling you to view USGS topos for your area of interest was located easily seaching his blog. Simply add the layer, wait a few seconds and the topo will appear.. toggle off when you don't need it... I'd love to see the ability to swipe the topo in/out with the google earth scene! Developed by 3D solar and KMZ streamed from the Google earth blog - here's the USGS topo layer KMZ.. enjoy! http://www.gearthblog.com/kmfiles/topomaps.kmz