Mikko Mononen's Blog - Highly recommended for anyone interested in AI navigation and pathfinding.
Recast Navigation - C++ navigation mesh generation and pathfinding. The Wiki contains a lot of core references I don't repeat here.
Building and Traversing Navigation Meshes with Recast and Detour - A video introduction to the process used by Recast to generate navigation meshes.
Navigation Mesh Generation via Voxelization and Watershed Partitioning with Mikko Mononen (Paid Membership Required) - A video interview/presentation of the process used by Recast to generate navigation meshes. (This is the interview that got me interested in the topic.)
Large-Scale Fluid AI Navigation in Complex, Changing Worlds (PowerPoint) - A presentation by David Miles that sparked Mikko's work.
More references are listed at appropriate locations within documentation.