Cap, this is already solved by Twitter Search. You can save any topic you are interested in following and expand those tweets. Just enter a term w/ or w/o a hashtag or a username into Twitter Search and you will see the tweets on the topic or related to a person (including people mentioning them.) The tweets can be filtered by top tweets/all/people you follow. In the left column, you can also select the "people" Twitter has identified as influencers on the topic. You can then delete the term from saved search when you are no longer interested in the topic.