Snap shot provides layers that look like speech bubbles when you hover an external link (place your mouse over a link) with a preview of the website. You can also use it for explanation of words to explain it in wikis, or put a link to youtube movies and play the movie directly in the ”speech bubble”.
The best is that you can get google maps inside the bubbles. Just ad a link to the adress.
You can also decide what kind of links that will have have snap shots. For example only external links, internal links, certain domains and so on.
So what is the disadvantage.. of course there are always something, when it´s free and fantastic…
Well, you have to show ads inside the bubble if a company has bought ads that is relevant to the content that you are showing…
Only to educational and governmental institutions has exemptions from showing ads..