Been messing around with this all day lol, its really fun.
Suggestion one: Add pages somehow? Or perhaps an option to enable pages or just all on one page.
Suggestion two: Messed around with a youtube video embedder, but doesnt work because of the auto-refresh, so i think i might just have to throw this one out the window:

function bb2html($str) {
   $patterns = array( "/\[link\](.*?)\[\/link\]/", "/\[url\](.*?)\[\/url\]/", "/\[b\](.*?)\[\/b\]/", "/\[u\](.*?)\[\/u\]/", "/\[s\](.*?)\[\/s\]/", "/\[i\](.*?)\[\/i\]/", "/\[center\](.*?)\[\/center\]/", "/\[scroll\](.*?)\[\/scroll\]/", "/\[yt\](.*?)\[\/yt\]/"); 

   $replacements = array( "<a href=\"\\1\" target=\"_blank\">\\1</a>", "<a href=\"\\1\" target=\"_blank\">\\1</a>", "<strong>\\1</strong>", "<u>\\1</u>", "<s>\\1</s>", "<i>\\1</i>", "<center>\\1</center>", "<marquee behavior=\"scroll\" direction=\"left\">\\1</marquee>", "<object width=\"480\" height=\"360\"><param name=\"movie\" value=\"http://www.youtube.com/v/\\1\"></param><param name=\"allowFullScreen\" value=\"true\"></param><param name=\"allowscriptaccess\" value=\"always\"></param><embed src=\"http://www.youtube.com/v/\\1\" type=\"application/x-shockwave-flash\" width=\"480\" height=\"360\" allowscriptaccess=\"always\" allowfullscreen=\"true\"></embed></object>"); 

which works by just putting the video id between the tags, like [yt]QV8eiSA4vqc[/yt].