Plugin adds "Extra shortcodes": [bloginfo show="name"], [site_title], [site_desc], [site_url], [date format="Y-m-d"], [time], [year], [month], [month_name], [day], [weekday].

• [bloginfo show="name"] - bloginfo params;
• [site_title] - Title of the site;
• [site_desc] - Description of the site;
• [site_url] - http://site.url;
• [wp_version] - 3.3.1 (WordPress version);
• [date format="Y-m-d"] - php date format params;
• [time format="H:i:s"] - php time format params;
• [year] - 2012, [year plus="3"] - 2015, [year minus="2"] - 2010;
• [month] - 3 (in march), [month plus="3"] - 6, [month minus="2"] - 1, [month plus="11"] - 12 (12 is maximum and it is not looped by default), [month plus="11" loop="1"] - 2 (14, but with loop it becomes 2=14-12);
• [month_name] - March;
• [day] - 8, [day plus="3"] - 11, [day minus="2"] - 6, [day plus="30"] - 31 (31 is maximum number of days for current month and it is not looped by default), [day plus="30" loop="1"] - 7 (38, but with loop it becomes 7=38-31);
• [weekday] - Friday;
• [hours] - 17;
• [minutes] - 35;
• [seconds] - 59;

View source of the Extra-shortcodes plugin.