After using basically every BBCode plugin available for WordPress–and finding every last one of them lacking–I decided to write my own. This one does not use shortcodes, as shortcodes apparently freak out when you want multi-line enclosed tags. My plugin applies filters to six hooks:
the_content
comment_text
the_excerpt
the_content_rss (strips BBCode)
comment_text_rss (strips BBCode)
the_excerpt_rss (strips BBCode)
The following tags are supported:
[b] [...]
JonathonWally
K.E. Ireland
Levi Montgomery