<>
Nick said
Somewhat in his spirit, here is one variation on Kit's style:
... yline(0, lstyle(grid) lw(*2)) xline(0, lstyle(grid) lw(*2))
That is,
1. You can make the extra -yline()- and -xline()- have the same style as
your grid lines.
2. But you can also make them a little more prominent by changing the
width.
Very nice. One thing that you might want to add is something like    
lcolor(gs13)   to make the axes just a bit more prominent than the  
rest of the grid. If you want them even more noticeable, use a number  
lower than 13, and v.v.
Kit Baum   |   Boston College Economics & DIW Berlin   |   http://ideas.repec.org/e/pba1.html
                              An Introduction to Stata Programming   
|   http://www.stata-press.com/books/isp.html
   An Introduction to Modern Econometrics Using Stata  |   http://www.stata-press.com/books/imeus.html
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/