The single best resource for fantasy cartographers is the Cartographer's Guild forum. https://cartographersguild.com

Mark Rosenfelder's site is an amazing rabbithole of world-building. http://www.zompist.com/howto2.htm http://www.zompist.com/virtuver.htm He's also written The Language Construction Kit and The Planet Construction Kit.

There's some great Google Plus communities around fantasy cartography, like Map-Making in Games https://plus.google.com/communities/105897774940532146183