I visit a lot of forums in my free time and I must say that this forum is a real gem. I do love phpbb software and the whole layout so its a good choice of platform.
Being a new member , I dont think my suggestions hold much weight but I'll just put them here anyway
First thing ,I would definitely like to see posts not being "auto merged" if you get what I mean. I think it confuses the hell out of people when you post a mile long message quoting different people at the same time. Also , the ones that want to quote my reply will have to eliminate all the other replies in my quoted message manually and this too can get a bit frustrating. In my opinion, we should encourage members to interact more with each other and form a bond and such things really slows its down. Its only via member interaction that any forum can grow. Of course , if you are keeping it for technical issues, there is no harm. Maybe it helps prevent spamming and thread bumping e.t.c.
Also , the chatbox and that "Where do all the members come from banner " all look very messy and is making the home page of the website look very clustered. It would be nice if you can provide the chatbox on a separate page. As far as a forum is concerned , chatbox really serves little purpose.