 <p>I use the <a href="http://webthumb.bluga.net" rel="nofollow noreferrer">http://webthumb.bluga.net</a> service for thumbnail generation. Robust, powerful, easy to use, and very reasonable rates. I have a high traffic production website using this service and it works very well. Given the difficulty of creating a robust web screenshot service, it's nice to have someone else do the hard work.</p>