Texture binding, texture generate, texture filtering, texture subimage, texture mapping by procedural definition & using imagefile, mipmapping, texture environment setting (modulate/decal), texture distorting, texture transformation, flipbook animation, etc
http://dis.dankook.ac.kr/lectures/cg08/entry/texture-mapping-예제

Texture filtering & environment paramaters
http://dis.dankook.ac.kr/lectures/cg08/entry/texture-filtering-environment-parameters-예제

wrapping parameters (REPEAT | CLAMP)

magnification/minification filter parameters (NEAREST | LINEAR | LINEAR_MIPMAP_LINEAR)

environment parameters (MODULATE | DECAL | BLEND | REPLACE)

Texture generation
http://dis.dankook.ac.kr/lectures/cg08/entry/texture-generation-예제

Multitexturing
http://dis.dankook.ac.kr/lectures/cg09/entry/OPENGL-Multitexturing

multipass-multitexturingsingpass-multitexturing
Billboarding
http://dis.dankook.ac.kr/lectures/cg09/entry/OPENGL-Billboarding

Before Billboarding
After Billboarding