We no longer use thumbshots.com to generate thumbnails of the websites because they slow down the loading time and some thumbs just don't get updated at all. We have now purchased a software to capture all thumbs and host locally. There is advantage of doing this, as PR juice flows from one site to another, we have removed the link of thumbshots.com on every page, so in theory, there won't be any PR juice "leaking" to them anymore, thus increasing our own PR juice :)