I've seen a few css frameworks add margin-bottom to heading elements in addition to a large line-height. Example from here.
h1 { font-size: 46px; line-height: 50px; margin-bottom: 14px;}
h2 { font-size: 35px; line-height: 40px; margin-bottom: 10px; }
h3 { font-size: 28px; line-height: 34px; margin-bottom: 8px; }
h4 { font-size: 21px; line-height: 30px; margin-bottom: 4px; }
h5 { font-size: 17px; line-height: 24px; }
h6 { font-size: 14px; line-height: 21px; }
However, I read here** that line height should be font size + 2-5pt. Which looks pretty fine to me. So is the extra space needed. Are there any typographic rules for how much space there should be under headers?
** Edit note: Link removed. The aisleone.net site has been hacked to launch drive-by malware. Alan G.