Off the top of my head:
- Canvas
- Processing / Processing.js
- Nodebox
- Cinder
- Raphael
- D3
- Paper.js
- CSS
Some of these have work-environments to make it easier but all of them are code based and can be done in a regular text editor. Except Cinder which is more advanced and required a platform to code C++ in. If nothing else though Cinder's website gallery and forum gallery has some really amazing projects.