Shout box would be good on every page. Maybe even as an auto fresh iframe so it works like an IM.

Ratings could work on more than thanks per posts(well thats what I've theorised the formula to be :P)[views per thread for example would be a fairer indication - obviously I'm dissatisfied with my declining rank :P].

allow image upload?(I have a pretty good uploader written in php)

The search thing is also annoying, could you make it so it still shows the previous search results even if it refuses to find new ones.

Also if you wanted to save on bandwidth you could use a full page table with Iframes so that the menu and footers doent need to reload.

I'm sure you guys know all your stuff but if you want any help from me I'll do my best to help