Sodipodi is general vector illustrating application for Linux/Unix and Windows. It uses W3C SVG as native file and in-memory image format and can do many neat things.
PTCPas is a free, portable framebuffer library, written in Free Pascal. It allows low-level high-speed graphics access on multiple platforms.
3D Multiplayer Hover Soccer
3D multiplayer realtime game with separately packaged 3D graphics middleware layer built on OpenGL. Runs on Linux, Win32, Mac OSX, Android - OpenGL/GLES 2.0 or later required