Cool! This is something I wanted to have and had started making for myself. Mine is much less useful than asciiflow but the thing I like most about it is that it allows writing and drawing more in the way I use my notebook. It's easy to write little blocks of text that aren't aligned along the left margin.

Feature request: In text mode, assign <enter> to move the cursor down a line and to the column that text entry began.

Here's my prototype: http://norstrulde.org/tty/tty.html