regarding the forum, i wouldnt change a thing comestically cos its simple and serves the purpose without being too flash or too basic and its right that the avatars and sigs arent available, cos it would just slow loading times down with all the members here.
regarding the site, i wouldn't guess what to add etc. i would say have you thought of changing the platform you use into an "all-in-one" cms platform like vBulletin4, where forums, cms and blogging etc is much easy to use and maintain.
<a class="postlink" href="http://www.vbulletin.com/index.php?do=screenshots" onclick="window.open(this.href);return false;">http://www.vbulletin.com/index.php?do=screenshots</a>
Its a bit pricey for the publishing suite license, but i'm sure you'd get enough donations if needed ;).
just a thought ... eff why aye etc etc