For a while now i have been using browsercam. This is one of the few sites where I seriously think that I should get payd access to. They offer great services for webdesigners. Ever thought "how would this look in browser X that i do not have?". This is he solution. Subscription is free, for a demo that latsts six days. After that you will have to pay.
However, that been said, I thought a lot about how their system works. Do they simply have a load of computers connected to a server and run scripts on them? The answer must be "yes". I found that out when one of my projects screencaptures had a hickup.
And guess what system had that hickup...==update: the project i linked to is taken offline, links in this article point no-where ===