Thomas Schulte

This plugin dynamically shows preview screenshots of hyperlinks as tooltips on your WordPress site.
For the tooltip effect a jQuery plugin called “qTip2” is used internally. 
Find more about this great project here: http://qtip2.com/ 
The thumbnails are provided by http://thumbsniper.com and its API.

ThumbSniper

This plugin dynamically shows preview screenshots of hyperlinks as tooltips on your WordPress site.

larsbachmann

Insert screenshots in your post and pages using a simple shortcode.
[screenshot width=”700″ alt=”WordPress”]wordpress.org[/screenshot]
Will show a screenshot of wordpress.org (700px width). 
Insert URLs without https://
This plugin uses mshots from WordPress.
It’s a very handy plugin, and you can use it on your portfolio page, webdirectory etc.
See screenshot examples at https://larsbachmann.dk/plugins/wp-screenshot

WP Screenshot

Insert screenshots in your post and pages using a simple shortcode.

ThumbSniper vs WP Screenshot