TiddlyWiki as SVG editor
During the weekend an idea jumped into my mind:
I'm thinking of something similar like a small MS Paint. Something like that is already existing, the ASCIIsvg Editor, but that is currently better suited for mathematical drawings and will very likely have to be modified a bit for inline and convient SVG editing. It's based on ASCIIsvg.js. This "library" has already been used to create a SVG-enhanced version of TiddlyWiki for math-equations. See the ASciencePad for this.
I wonder if anyone before me had the idea (and wrote it down) of an inline SVG painting tool...