In addition to the introduction and the API reference, several people have contributed online tutorials on using various parts of SDL.
Tutorial SDL - Primera parte Covers: Basics of using SDL in Spanish The Game Programming Wiki: SDL Tutorials Covers: A large number of tutorials covering SDL topics Dev Hub Game Tutorials Covers: Introction to SDL, using CodeBlocks Direct3D 9.0 with SDL Covers: Using SDL with Direct3D for graphics SDL and OpenGL Covers: Using SDL and OpenGL on Mac OS X Beginning Game Programming Covers: A series of tutorials on game concepts geared for SDL developers SDL corner - Audio with SDL Covers: Lots of advanced information on using SDL's audio support SDL corner - Using OpenGL with SDL Covers: Lots of advanced information on using SDL with OpenGL Sol's Graphics for Beginners Covers: Setting up SDL with Visual C++ 6.0, basic graphics programming SDL Setup Guide 1.1 Covers: Setting up an SDL project with Visual Studio .NET Tutorial / Einsteigerkurs in das Programmieren mit der SDL in C Covers: The basics of using various features of SDL, in german Help! How Do I Move An Image? Covers: Using Pygame to move images around in a simple game SDL-Grundlagen und Grafik Covers: A german tutorial on SDL basics and graphics How I Rendered the Dungeons on SDL Covers: Exploring the code used to render 2D mazes in DungeonMaker OpenGL Tutorials (by Marius) Covers: Setting up SDL and OpenGL, Quake 2 models, OpenGL graphics topics. GFX with SDL (by Marius) Covers: A very nice set of tutorials covering using SDL with Dev-C++, 2D graphics, and sound Roger's SDL Tutorials Covers: SDL_mixer, SDL_RWops