This plugin uses the Thumbshots.RU API to replace special tags in posts with website screenshots.
This plugin allows any user to add previews of websites right in the content of their posts using a simple [thumb]http://domain.com[/thumb] format. Users may also "optionally" turn on mouseover previews. No purchase or registration is required to use the plugin. Optional upgrade enables PRO features such as "Full-length Captures", "Free Width Captures" and "Refresh on Demand".
Take a look at Thumbshots.RU for more information (http://www.thumbshots.ru/en/ "Website screenshots provider").