Recently it's come to my attention that there are a crap load of graphics/gaming libraries. From what I understand:
1. LibSDL - basically a cross-platform wrapper for the 2D portion of each OS' native graphics API (like pixel operations, not the more advanced stuff) along with some networking support
2. Allegro - basically the same as LibSDL minus networking, but with support for sprites, more support for playing sounds...targeted more towards gaming than media...
3. cairo - just 2D vector graphics, used in Gtk
4. SFML - basically a C++ version of LibSDL
5. ClanLib - haven't checked into it yet
6. OpenGL - just 3D graphics
Anyone have anything good or bad to say about any of these? Anything to correct? Did I miss any major ones (besides like XNA, talking cross-platform libraries here)?