We now offer a free service to create thumbnails on the fly and display it on your website.
You can specify cropping size, output size, quality level, delay time ( good for snapping flash sites ), force an update and other things.
Interested? Check out http://www.artviper.com/tools.php to get an idea how it works.
Who uses it already? To name a few:
newsreaders ( feeds.popoever.net, feedburner, netvibes.com, pluck.com and others )
Requirements - just add the backlink as described on our tools page to the pages that display the thumbnails. Done :)