body {
max-width:800px;
font-family:georgia, serif;
}
h1 {
text-shadow: #555 3px 3px 4px;
}
h2 {
text-shadow: #f00 0px -5px 10px;
}
a {
font-size: 120%;
text-shadow: #555 2px 2px 0px;
border: 1px solid black;
}
p.shadow {
color: #ccc;
text-decoration: bold;
text-shadow: #000 2px 2px 2px;
}
The different properties from left to right set the colour of the shadow, the left/right and top/bottom offsets of the shadow (negative values move the shadow left/up, and positive values move the shadow right/down), and the amount of blurring for the shadow.
If you want to know more, visit the CSS3 spec - there's a lot of text there, but you might find some of it interesting.