I was trying to figure out the easiest way to make a contact us form and learned through the wordpress.com support page that you can just write [ contact-form ] (without the spaces) and wordpress does it for you. Pretty neat! Note my seksy new contact us page linked in the upper right 😉
The capabilities are pretty awesome if you have a paid blog, but WordPress.com has a pretty neat list. Hopefully more will be added with time.
See full list here: http://en.support.wordpress.com/shortcodes/
For now, I leave you with a pretty video I made…Inserted into this post easily with shortcode.