How to add a simple paypal donation link

function donate_shortcode( $atts ) {
    extract(shortcode_atts(array(
        'text' => 'Make a donation',
        'account' => 'REPLACE ME',
        'for' => '',
    ), $atts));

    global $post;

    if (!$for) $for = str_replace(" ","+",$post->post_title);

    return '<a class="donateLink" href="https://www.paypal.com/cgi-bin/webscr?cmd=_xclick&business='.$account.'&item_name=Donation+for+'.$for.'">'.$text.'</a>';

}
add_shortcode('donate', 'donate_shortcode');

Replace the default ‘account’ with your paypal email address, and output using [donate]. Remember you can override the default ‘text’ too in the shortcode. You can style this link with css easily.