Automatic LaTeX → BystroTeX conversion
I have tried to write a program which converts a LaTeX document into BystroTeX, for example replaces every $x$ with @f{x}. This only covers a very limited subset of LaTeX. The problem is, every person writes LaTeX in their own way. For example, some people write \beq instead of \begin{equation}. Then, the converter would have to be customized (by editing its source code).