ProcessWire - ReadingTime Based upon: http://briancray.com/posts/estimated-reading-time-web-design

PageReadingTimeHook.module

<?
wire()->addHookProperty('Page::readingTime', null, 'readingTime');
function readingTime($event) {
    $page = $event->object;
    $words = str_word_count(strip_tags($page->body));
    $m = floor($words / 200);
    $s = floor($words % 200 / (200 / 60));
    $minutes = $m == 1 ? __('Minute') : __('Minutes');
    $seconds = $s == 1 ? __('Second') : __('Seconds');
    $event->return = "$m {$minutes}, $s {$seconds}";
}