I think url2png is really cool, but I was a bit pissed when from one day to the next they went to a subscription model and added sign-up links to all screenshots. Their fair right, of course, but no fun if you just started using it.
I have been using the service for over 3 months and I remember telling the founder I would pay for it. Well. looks like I am going to send my check now :). Gladly.