I do agree that it's rather flat, but I have a hard time adding subtle texture, partly because I don't what are good background or border image or styles, and partly becaue I'm slightly design impaired.
As someone who is also a little design impaired, I always find it useful to play around with one of the many punbb styles downloadable from punres.org.
One attractive style that could probably be adapted to your needs for example (ie it's primary colours are red) would be something like RedLife for PunBB 1.2: http://www.punres.org/viewtopic.php?id=3770 . Just dump the (rather large) header image, dump the crazy body background image, add your own header image and adapt the title font and size, and you have could another style option for your users.
Maybe also have a look at http://www.arsamania.ru/forum/ - a Russian fan site for British soccer team Arsenal. It is a very nicely styled punbb forum that is similar in concept to your Redsox site, and the Arsenal colours are even the same as the redsox ones. The developer adapted one of the VB style themes from punres to get his look, and it works well.
A final snippet: while the forum width has been reduced from 100%, the whole forum is still left aligned, so I now only see a space on the right-hand side only of the forum. The whole forum probably needs to be centred, or equal padding applied to both left and right of the main box containing the forum.
Agreed that a WYSIWYG editor mod makes a big difference to users, esp non-tech or casual ones. Pity they add weight though to the page. Which one did you use?