I think it would very useful to permit every user to add to their profile a list of Latex command, so that they are readily at disposal.
For instance, in all of my .tex files I add in the preamble
which is handy to put an 'and' in the middle of the equation environment.
Don't you think it would be nice to add such a feature in the StackExchange network?
I tried to put a command in my "about me" section. The result is that, whenever I am in a page where my avatar is showed (e.g. a question I posted or a question I replied to) and I hover on it to let my description appear, then the command works in the preview. So I guess it should be very easy to add this feature!