This list currently skews heavily non-commercial, but feel free to edit to your taste and we'll figure it out. I'm aiming for projects you can actually chat with the creators about on the FoC forum. In alphabetical order for lack of a better idea.
0D: Component-based software using drawings as source code
Blawx: A block-based programming language for drafting rules and laws
Codeflowcanvas: An interactive visual programming system
Freewheeling Apps: Durable programs that are easy to download, run, modify, share
Glamorous Toolkit: An interactive programming environment with extensible domain-specific UIs
Hest: A tool for making highly interactive simulations using direct manipulation
Holograph: A visual coding tool based on propagator networks
Leibniz: A digital scientific notation with an interactive authoring environment
Object Network: A 3D operating system with no apps, just files
Subtext: Experiments in radically simplifying programming
Tom's Visual Probabilistic Programming Language
Less active projects/creators
Ceptre: A programming language for interactively prototyping rule systems like game mechanics
Glance: A visual Haskell
Lamdu: A next-generation programming language and IDE
Mu: A memory-safe programming language and OS bootstrapped up from machine code
Ratio: A visual tool for creating tools
Teliva: A sandboxed platform for text-mode end-user programmable apps
Related
This page was seeded from Duncan Cragg's project comparison spreadsheet