Came across this wonderful web site http://www.thumbalizr.com/ . Just enter the url for which you want to have a snapshot image . It will generate it in realtime and can be downloaded. This is a very useful tool for bloggers/website users who post articles with web screenshots. I tried generating web screenshot for outlook.com (generated pages are in german) - for my previous blog post. May be if the service provider uploads the generated image to a free image hosting provider - it may give them a extra edge over other online tools. Currently generated images (user is provided with options to choose the size) needs to be manually downloaded and then can be used in internet via any free image hosting.
Other free service which i tried is convertwebpage . Its easy and quick in conversion of the webpage to a image which can be downloaded . Downloaded image can be hosted in any free picture hosting provider site.