This code will add a link to make the person a 'buddy' in their mini profile.

You choose where to put the link, by putting the code into the mini profile templates ( => Mini Profile Templates).

<script>
var a = '{display_name}';
var x = (a.match(/view_profile\/user\/(.+?)(\/|"|\/")/))?RegExp.$1 : '';
if(x != vf_username){
    document.write('<a href="/action/add_buddy/user/'+x+'">Add to Buddies</a>');
}
</script>