Here is a few things I would like to see:

1.) Better parsing of unwanted code in posts. I noticed that < input> without the space gets run - not sure about other things. I also noted that script* words tend to be changed to sc< x >ript regardless of case and if they start with < ? or not.

2.) Maybe a [ code ] [ /code ] tags in the post editor to paste code and configuration changes. I don't like using [ quote ] for this.

3.) A way to use an external SMTP e-mail host/account. I want to use google apps rather than my host's default e-mail service (because it's slow - takes about ~10 minutes to receive e-mails from the forum)

4.) Maybe a way to make the whole thread box clickable instead of just the linked text in it.

That's about it for my suggestions, otherwise this forum system works pretty well and fast.

Edit: I tested the [ code ] tags and found out it works, only it adds php tags to it. I'm going to edit it now to remove that 'feature'.

please replace this code of header.php

  if ($tdb->is_logged_in()) echo "
<li><a href='index.php' title='Forum Home'><span>Forum Home</span></a></li>
<li><a href='".$_CONFIG["homepage"]."' title='Site Home'><span>Site Home</span></a></li>
<li><a href='showmembers.php' title='Members'><span>Members</span></a></li>
<li><a href='search.php' title='Search'><span>Search</span></a></li>
<li><a href='board_faq.php' title='Help Faq'><span>Help Faq</span></a></li>";
else echo "
<li><a href='index.php' title='Forum Home'><span>Forum Home</span></a></li>
<li><a href='".$_CONFIG["homepage"]."' title='Site Home'><span>Site Home</span></a></li>
<li><a href='search.php' title='Search'><span>Search</span></a></li>
<li><a href='board_faq.php' title='Help Faq'><span>Help Faq</span></a></li>";
echo " "

with this

if ($tdb->is_logged_in()) echo "
<li><a href='index.php'>".stripslashes($_CONFIG["title"])."</a></li>
<li><a href='".$_CONFIG["homepage"]."'>Home</a></li>
<li><a href='showmembers.php' title='Member'>Member</a></li>
<li><a href='search.php' title='Search'>Search</a></li>
<li><a href='board_faq.php' title='Help Faq'>Help Faq</a></li>";
else echo "
<li><a href='index.php'>".stripslashes($_CONFIG["title"])."</a></li>
<li><a href='".$_CONFIG["homepage"]."'>Home</a></li>
<li><a href='search.php' title='Search'>Search</a></li>
<li><a href='board_faq.php' title='Help Faq'>Help Faq</a></li>";
echo "

and this

<td id='logo'><img src='".$_CONFIG['logo']."' alt='' title='' /></td>


with this

<td><div id='title'><a href='index.php'>".stripslashes($_CONFIG["title"])."</a></div>
<div class='sub-title'>sub title of the forum</div></td>

and change this code of style.css

#logo {
background-color : #7997c0;
padding : 0px;
}

with this

#title {
padding:10px;
font-size:35px;
text-shadow:#FFF 0 0 5px;
color : rgba(255,255,255,0.9);
background-color : rgba(0,0,0,0.9);
-webkit-border-radius: 6px;
-webkit-box-shadow: 6px 6px 6px rgba(0,0,0,0.4);
-moz-border-radius: 6px;
-moz-box-shadow: 6px 6px 6px rgba(0,0,0,0.4);
}

#title a, #title a:visited, #title a:active{
color : rgba(255,160,35,0.9);
text-decoration:none;
}

#title a:hover{
color : rgba(255,255,255,0.9);
text-decoration:none;
}

.sub-title {
font-size:25px;
text-shadow:#FFF 0 0 5px;
color : rgba(35,160,255,0.9);
}

this code will make upb more beautifull and SEO friendly