TeXmacs is awesome, I used it in grad school to take notes during QFT lectures and I could follow along because the shortcuts are just so intuitive if you already know latex: for example in math mode, ^ enters superscript, _ enters subscript, you can access greek letters by tab completion from the roman alphabet characters like \alpha is a+tab, \delta is d+tab, \Delta is D+tab (capital D tab). It's awesome, although a little buggy in the less used bits like the graphics maker.

Still, it has a load of potential, it just needs a little more love (developers and money I suppose).

EDIT: little tidbit, much like the online org-mode manual, judging by the typeface and the color of the hyperlinks, I bet this article itself was written in texmacs and exported to html.