Limiting a div height to two lines of text inside it?

div {
    height: 1em; // that's one line, 2em for 2 lines, etc...
    line-height: 1em; // the height of one text line
    overflow: hidden;
}

This will display a div with a height the size of the current font size, and any overflow is clipped. As long as line-height and height are equal there will be one line of text. The proportion of height/line-height determines the number of lines displayed.