PBTweet is a Twitter-enhancement available as a bookmarklet, GreaseKit script and GreaseMonkey script, which allows you to enhance and tweak Twitter in Safari, Chrome and Firefox.
What are some of the enhancements provided by PBTweet? You can thread conversations, PBTweet puts quick-response buttons directly under each tweet so you can translate the text, re-tweet, and use a via @ tag.
URLs shortened using tinyurl.com, bit.ly, ff.im, twurl.il and is.gd can be expanded with a mouse-over. Pictures shared with twitPic.com, tumblr.com, brightkite.com ,MovaPic.com, 12seconds and bcphotoshare.com are thumbnailed. You'll never have to click through to keep reading, PBTweet enabled infinite-scrolling on your Twitter feed. Check out the video below to see it in action.
Safari/Chrome users can take advantage of PBTweet via bookmarklet or GreaseKit script. Firefox users don't get a bookmarklet, but there is a Greasemonkey script available.