With thumbalizr you can take screenshots of any webpage you want.
Use it for your presentations, documentations, visualisations or your webpage.
Just enter the target-URL and press the “thumb it”-button. Wait a moment and a screenshot of the desired page will be taken. You can choose between a screenshot with a fixed height of the screen or the complete webpage.
What’s real cool about this tool, unlike a lot of these simple online tools, is that they have exposed an API so you can automatically have thumbnails generated on your website or blog.
Link: http://www.thumbalizr.com/