px for font sizes

Sacrilege, I know. There are perfectly good ways to get consistent font sizing and I really should use them but Internet Explorer is the only browser that I can think of that doesn't resize text. If the majority of your audience uses IE, then be nice to them and don't use pixels. Otherwise, I figure with IE7 supporting it, pixels are the new ems.

When using pixel sizes, I also get to be sparing in my usage. I specify it on the body and any headers that need it. Inheritance is less of an issue (how many sites have you seen list items inexplicably smaller than the rest of the content like it was less important).