Twitter has an official app for Safari and this is pretty cool. It is called simply Twitter for Safari and it aims to keep you up to date with real-time trends and information based on the web page you are currently visiting.
And, if you visit a site with a connected Twitter account (or if the site`s authors have their own accounts that link back to the site in their Twitter bios), it will display it for you in the browser bar.
In short, the Twitter for Safari add-on lets you see in a sidebar the tweets on a particular topic.
Twitter can also keep track if the webpage you are on is gaining any sort of traction in Trends, give you an instant link to post your own tweets and see related tweets in regards to the topic you are currently reading about.