Current version of raylib is quite complete and functional but there is still a lot of things to add and improve. Here it is a wish list of features I would like to add and functions to improve.
Note raylib source code has multiple TODO points with pending things to review and improve. Check GitHub Issues for further details!
raylib 1.x
Basic GPU stats sytem (memory, draws, time...)
Improved custom file-format (.rres) and packaging tool
Procedural image generation functions (spot, gradient, noise...)
Procedural mesh generation functions (cube, cone, sphere...)
Touch-based camera controls for Android
Gamepad support on HTML5
raylib 1.6
[DONE] Lua scripting support (raylib Lua wrapper)
[DONE] Redesigned audio module
raylib 1.5
[DONE] Support Oculus Rift CV1 and VR stereo rendering (simulator)
[DONE] Redesign Shaders/Textures system -> New Materials system
[DONE] Support lighting: Omni, Directional and Spot lights
[DONE] Redesign physics module (physac)
[DONE] Chiptunes audio modules support
raylib 1.4
[DONE] TTF fonts support (using stb_truetype)
[DONE] Raycast system for 3D picking (including collisions detection)
[DONE] Floyd-Steinberg dithering on 16bit image format conversion
[DONE] Basic image manipulation functions (crop, resize, draw...)
[DONE] Storage load/save data functionality
[DONE] Add Physics module (physac)
[DONE] Remove GLEW dependency -> Replaced by GLAD
[DONE] Redesign Raspberry PI inputs system
[DONE] Redesign gestures module to be multiplatform
[DONE] Module raymath as header-only and functions inline
[DONE] Add Easings module (easings.h)
Any feature missing? Do you have a request? Let me know!