Do you think it would be feasible / possible to put together a basic header file of "standard" LaTeX macros that we might be able to use when typing up MO questions or answers? I mean, basic objects like $\mathbb{R}$, or $\mathbb{C}$, or $\| \cdot \|$ (as a macro '\norm'), or you think that this idea is doomed due to the large variety in the way people use LaTeX on MO?

I think it might simplify the typing for several regular MO'ers, while keeping the markup of their post shorter and cleaner?

`\newcommand`

. So if you start you post by`$\newcommand{\R}{\mathbb R}\newcommand{\C}{\mathbb C}$`

$\newcommand{\R}{\mathbb R}\newcommand{\C}{\mathbb C}$ you can use \R and \C for $\R$ and $\C$ in your post. (One should be a little careful when using newcommand, for example, you should avoid using it in the title. Apart from making the title less readable, it could cause other problems, see here and here.) $\endgroup$