Markup OverviewExpress thoughts quickly and easily on any webpage. Share ideas with coworkers and friends. Since Markup works in your browser, so there’s nothing to download and install. Just drag the Get Markup icon into your bookmarks bar. When you want to make notes on a webpage, click your bookmarklet to load the Markup toolbar. Publish when you’re ready to share your thoughts. (from the Markup website)
To read more and get the Markup tool bookmark, click the above hyperlinked text.