Auctex like c++ mode

[Glen Stark]

Hi everyone.

I really like the way auctex increases the font size (face size) for 
sections and subsections in latex mode.

I've always thought it would be really nifty to do the same thing for the 
signature part of function definitions in c-modes.  In case I screwed up 
the vocabulary, what I mean is this:

void i_want_this_big(maybe the params too, i'm easy)
{
/// I want the body normal
}

I also thing it would be really sexy if nested braces and parenthesis 
could be distinguished by varying face sizes.   Maybe once I saw this in 
practice I'd change my mind, but I'd like to try it out.

It seems to me that this should be easy enough to do, but I don't know 
how to do it, and I haven't been able to find any instructions or theme 
or anything online... perhaps because I'm not searching for the right 
terms.

Can anyone explain how I might go about doing this?  I'm an apprentice 
level elisp programmer.

Cheers,

Glen