Site Collector makes this task simple, just add a URL and the capture time from 10 minutes to 24 hours.
Once set you are greeted with multiple options such as ‘snapshot’ for taking a manual shot, QuickLook to get a look at the snapshot quickly, open webpage and the option to open the screenshot in Preview.
This tool produces high quality images of the website without hassle or manual work! Just enter the URL and the app will take care of the rest.
Updated on Oct 29 2012