WYSIWYG: AbiWord 2.4 has nice mathematical typesetting features it seems: screenshot by Martin Sevior. The horizontal spacing in the formulas still looks horibble to me, having spent so much time with TeX. But I guess not many users do care that much about formula aesthetics. Update: I am not an AbiWord user. I only based my observation on Martin's screenshot. I can't even think about using anything other than TeX for typesetting mathematics.