Supported BBCode tags:

bold, [b]text[/b]
italic, [i]text[/i]
underline, [u]text[/u]
strike, [s]text[/s]
image, [img]image_link[/img]
url, [url]link[/url]
url as text link, [url=link]text[/url]

With the addition of:
quote (or just hit reply and use quote button), [q]text[/q]
paste.org code snippet where int is the uri digits [p]int[/p]