Nomnoml
These tools show up from time to time here, and I can appreciate the technical side of things and effort put into building the tool. However, I cannot imagine using something like this in practice - either at work or for my own uses. It's so much easier just to select, drag and drop graphical elements instead of spending time learning a specific markup language and typing everything out, hoping that the elements will appear approximately where you wish they would. Maybe it's not too bad for very simple diagrams but unmanageable for anything complex. All in all, I think it does not solve any problems and merely adds an additional layer of complexity.