Good site topsy.com allows to find how many sites mentioned your brand name during last 3 days/7 days/ 30 days/all time.
You can check also how many tweets got your brand name, how many images and video speak about your brand name.
You can exclud retweets and via mentions , just add -rt -via to the search query.
You can create email alert to get by email all new references of you brand name.