While these have been largely a footnote, the embeddable tweets are pretty nifty:
...embeddable Tweets [are] a new way to add any Tweet to your website just by copying and pasting a line of code... Visitors can follow the author with a single-click, and reply, retweet, or favorite the Tweet without leaving the pageNow if they can just automate this so new code doesn't need to be added each time...