Reducing the uniqueness of a browser's fingerprint seems like a more valuable privacy investment than a DNT header that may or may not be adhered to by the websites you visit. Are any of the major web browsers actively working on this?
There are add-ons and extensions available. To give an example I have an old firefox setup here with these add-ons: RefContol (forge referrer), UserAgentSwitcher (user agent manipulation), NoScript (block all scripting and therefore many tracking scripts), AdBlock (not sure is this helps to be honest), CookieMonster (easy cookie management), RequestPolicy (blocks request from your browser, helps with cross site scripting attacks; note this add-ons makes for a painful user experience unfortunately). Of course Java and Flash are disabled but if you don't want to disable them there are add-ons like BetterPrivacy for Flash that deal with them too. Note this setup is somewhat outdated and I have not kept up with recent developments. Finally all of this is useless if you don't also proxy your IP.
