The how to section covers a multitude of ways to accomplish everyday magic in concrete5.
Using Google custom fonts
Below is the call to Google for a custom font called "Molengo". Just put this in your template header.php file before the tag and make sure you don't re-declare it in your site css and you should be good to go. Full instructions are here.
<link href="http://fonts.googleapis.com/css?family=Molengo:regular"
rel="stylesheet" type="text/css" >
<style>
body {
font-family: 'Molengo', serif;
font-size: 14pt;
font-style: normal;
font-weight: 400;
text-shadow: none;
text-decoration: none;
text-transform: none;
letter-spacing: 0;
word-spacing: 0;
line-height: 1;
}
</style>