Here's a short notebook on how to create a new cell style: http://members.wolfram.com/mmorrison/Notebooks/CreatingANewCellStyle.nb
This will create a new cell style for the private stylesheet of the file (notebook, CDF) in question. If you want to add a new cell style to the default Mathematica stylesheet, that is a little more involved.
Suggestions can be sent directly to firstname.lastname@example.org
, although I and others who monitor this forum can be contacted as well.