Font Sizes & Font-Family - a handy page for webdevs
The domain is no longer up, but the Wayback Machine has a good copy of it.
In a nutshell: all on a single, you can see the different CSS values for font size (and common font families) for your reference or viewing pleasure or whatever...
http://web.archive.org/web/20040625035645/www.sam-i-am.com/work/sandbox/css/fontsizes.html
(original link, tho' it is dead: http://www.sam-i-am.com/work/sandbox/css/fontsizes.html )