I would like to see....
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'Search forums' / 'Search threads' boxes being at the top of the pages close to 'Add Reply' etc., as where they are at the footer they get missed by the majority.
View First Unread - (at top of threads) saves hitting the back button and then the small arrow on the forum page to go to the first unread post in a thread
Social Bookmarks - digg, Delicious etc.
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Google ads (or similar) - with the ability to display adds in a number of places (between say 1st & 2nd post), inside the first post, in the header / footer. above the quick reply etc. All these being controlled by usergroups as to who does and does not see the ads.
When a restriction is in place for a period of time, give a countdown in seconds - saves people clicking the search button time and time again (which probably is a greater load that running a countdown).
+1 :)