Just a quick update: most bbCode tags are now working. At the moment, the included ones are:
Bold: [B ][/B ]
Italics: [I ][/I ]
Underline: [U ][/U ]
Direct link; a la
http://www.google.com: [URL ][/URL]
Text link; a la
Search Engine: [URL=... ][/URL ]
Image: [IMG ][/IMG ]
Strikethrough: [S ][/S ]
Text color: [COLOR=... ][/COLOR ]
Text colour

: [COLOUR=... ][/COLOUR ]
Text col

: [COL=... ][/COL ]
Text size: [SIZE=... ][/SIZE ]
Of course, these tags will be used without the spaces that I've added before the ']'. And they are case insensitive. I've added a few color synonyms, as I'm sure some people were tired of the American spelling

.
Size works slightly differently at the moment then it does here. Instead of a scale 1-7, it is now pixel height. So [SIZE=10 ][/SIZE ] would make the containing text 10 pixels high (consider the size options in MS Word as an example).
Other tags yet to be implemented:
Quote - no source: [QUOTE ][/QUOTE ]
Quote - with source: [QUOTE=... ][/QUOTE ]
List: [LIST ][/LIST ] - each new item will be identified with a new line
Plus some more special tags just for Web Riddler.

After getting the bbCode done, smilies will be a breeze.

On a side note with regards to IMG tags. We've had problems here when images are too large, where they stretch the forum's width. I've had similar problems with layout when -*test*-('")ing with large images. So if possible, I'll probably thumbnail images if they are too large with a link to the full image.