Ask HN: Any decent web apps for generating web site screenshots?

I need an app that can generate large-ish (800px or 1000px wide would be nice) web site screenshots quickly (within a couple seconds). I don't mind paying. On Google I see a lot of apps that do this but for the most part they seem to be slow and/or output small image sizes. Is there a service that does this that you have personally used and can recommend? EDIT: Just found http://url2png.com/ which looks like it might be the winner, but definitely open to other (cheaper?) options.