FontStruct is proprietary flash.
Typism is dead, no one worked on it for ages.
http://prototypo.io is new, active, libre, Angular, on github, but! it suffers from the classic problem of processing and such; designing visual things isnt best done by writing code. Its why metafont didnt catch on - https://www.google.co.in/search?q=why+metafont+didnt+catch+o...
That's why I help start http://metapolator.com which will become a much more powerful online font editor, because it allows you to design typeface families instead of letters.
Hey dave,
Currently in Prototypo, users design fonts in a visual way only. Using code will come later, when we can make it user-friendly enough and fully integrated in our visual editor.
Anyway, the future looks bright for open-source online type design software. There's a little competition and many possibilities for collaboration. That can only be good!
FontStruct - build a face with pre-defined blocks, uses Flash, proprietary, sponsored by FontShop. 6 years old.
http://fontstruct.com/
typism - development history and novel path drawing, uses SVG+JS, MIT licensed. Fonts are distributed under OFL. 5 years old.
http://typism.appspot.com/