Untested in 2.8/2.9, but this is tested as working on 3.0.1... :)
// Intended to serve as an example only, modify the code to suit your requirement
add_filter( 'manage_users_columns','new_users_column', 10, 1 );
function new_users_column( $cols ) {
$cols['preview_foo'] = 'ChangeThisValue';
return $cols;
}
add_filter( 'manage_users_custom_column', 'new_users_column_data', 10, 3 );
function new_users_column_data( $existing_string, $col_name, $user_object_userID ) {
if( 'preview_foo' != $col_name )
return $existing_string;
$preview = get_author_posts_url( $user_object_userID );
$name = get_the_author_meta( 'user_login', $user_object_userID );
return "<a href='$preview'>$name</a>";
}
Hope that helps.. ;)