It would be very useful to be able to use \displaystyle, \textstyle,
\scriptstyle, and \scriptscriptstyle in <math> markup (mostly \textstyle). For
an example, please see my sandbox at http://en.wikipedia.org/wiki/User:Bkell/Sandbox
Currently things like <math>n\choose k</math> render in display style, which is
fine for displayed math (i.e., math set aside in its own little box on a line by
itself), but is far too large to be used comfortably in running text. All four
of \displaystyle, \textstyle, \scriptstyle, and \scriptscriptstyle are defined
in both plain TeX and LaTeX.