However i would like to help others in their journey for OpenGL. I strongly recommend reading these resources instead of buying many books. Switching to resources too much without fully giving time to them just wastes time and demoralizes us.:-
1. OpenGL redbook: it's enough for studying OpenGL concepts. Click this link
2. The simplest and nicely described tutorial on OpenGL + shaders (i.e. covers OpenGL ES 2.0 also ).
Click this link pointer to http://duriansoftware.com/joe/
3. Nehe (Neon Helium) GL tutorials. Link
4. Going to learn about rendering models, UV mapping etc. Link
5. GLSL, OpenGL ES 2.0. Link
6. Good samples for some of important OpenGL techniques. Link
If you know more links then please let me know.