Ehh... I'm really hesitant to program any BB code. I hate dealing with strings ((Text)). They're not as easy to manipulate as numbers. I COULD program a BB code system, but it wouldn't be able to check for a closing tag. If you left a tag open, it would kill the site. What's worse is it would all be stripped when you edit your post, since I have that automatic link thing running.
As for files, I dunno. That could be a big flaw in the code if anyone were to upload a bad file. One virus or hacking tool, and the site's done.