Updated 20-Sep-2023
Diagrams.net -- previously draw.io -- is a neat web/web 2.0 diagram editor. It supports Google Drive and also VSCode integration. Currently I usually just use Inkscape and draw whatever I need by hand. It is usually faster, and can embed as an SVG or simply output a PNG file. However, if one does a lot of drawing, then this kind of tool could make things faster and/or tidier.
See their blog for updates.
- Google Drive integration
- VSCode integration, including github.dev integration
- Notion chrome extension (I couldn't get this to work)