I'm sure most of you have seen the Reddit section, but if not, it's an excellent place with many inspiring photos. From the tabs at the top you can choose the type of images you'd like to view by category, such as agricultural and botanical. There's even a sub-section devoted to Geology. I'll link to my favourite section, which is a place for people to post inspiring landscapes from around the world.
http://www.reddit.com/r/EarthPorn
http://www.reddit.com/r/EarthPorn
