I've noticed an awful lot of folks asking about tectonics and climate recently, so I thought I'd start a thread with some resources. Post up your favorites, and if we can get a really useful thread built, I'll sticky it.

The whole kit and kaboodle (planetary considerations, climate, tectonics, ecology):
A Magical Society: Ecology and Culture ($ pdf downloadable ebook): http://rpg.drivethrustuff.com/produc...d-Culture?it=1 -- this book is worth the money and more. It's my number one worldbuilding resource.

Tectonics information:
The Wilson Cycle by Lynn S. Fichter at the James Madison University: http://csmres.jmu.edu/geollab/fichte...on/Wilson.html - this demystified tectonics for me, at least to a working level. Awesome.

Water Cycle:
http://www.cartographersguild.com/sh...he-right-place -- this thread has grown over time to include TONS of information about water on a planet. Must-Read.