Awesome highlighter is a neat tool - if you want to send someone a link to a document or newspaper article, for example, you might wish to highlight a particular section of the document for the recipient's attention. To do that, sumbit the url of the page to awesomehighlighter, highlight the section with the yellow marker, and click done. Awesomehighlighter creates a url for the highlighted page that you can pass along to your contact...here's a practical example.
This reminds me of an even more impressive tool, CiteBite, which I posted about a year ago at ircworld. It does essentially the same thing as awesomehighlighter, but it creates a within-page anchor directly to the highlighted segment, so the recipient doesn't need to scroll to find it. And best of all, there's a Firefox extension that allows you to add this useful tool to your right mouse button menu. Just highlight text on any page, right click, and CiteBite creates the url for you. Really awesome!