While the quality of website pictures captured with these screen capture utilites is excellent, the only limitation is that you are tied to the web browser. You can grab the image of the entire web page only when the site itself is opened inside the web browser.
The good news is that there's a better screen grabbing option available for free. Nathan Moinvaziri has developed WebShot, a tiny 52 kb app for taking screenshots of webpages from Windows Command Prompt. [Download WebShot]
Here's a quick guide to use the Webshot screen capture utlity:
Screen capture a complete website (even areas below the fold)
webshot.exe /url "http://www.screen-capture.com/"
Takes a screenshot of CNet website and clips the image off at 600 pixels high
webshot.exe /url "http://www.cnet.com/" /bwidth 600
Takes a full screenshot capture of CNet website and creates a thumbnail of it with the size 800×600
webshot.exe /url "http://www.cnet.com/" /width 800 /height 600
With Webshot, you can also generate thumbnails of websites like Alexa does. The program is Windows only and sometimes the size of captured images can run into a couple of MBs with the default settings. You can however tweak the quality of images to reduce the filesize.
If you are on Mac, try Paparazzi which is again free and can grab stills of long web pages. The program displays a preview and you can save the screenshot to PNG, JPEG, TIFF, or PDF. Paparazzi! is available as a universal binary.
webkit2png is another command line website screen capture utility for Mac based on Safari rendering Engine. It's basically a Python script and creates png screenshots of webpages. Here's how to use webkit2png:
python /path/to/webkit2png http://www.apple.com/
For Linux fans, khtml2png is a command line program to create screenshots of webpages. It uses the KHTML engine, but runs from the command line and doesn't flash windows up. It can be used to generate thumbnails of Web pages.
If you are a professional web designer with the budget, I would recommend BrowerCam online screen capture service. BrowserCam is essentially for testing any site design across different browsers and operating systems with various permutations and combinations of brower plugins, internally it takes high-resolution screenshots of webpages which you can then save to you hard drive. Allows capture of Secure websites also. Free 24 hour trial available with 200 capture limit. No AOL support yet.
HTML To Image is another Screen Dump utility that can parse web sites and save a screenshot of the page in GIF, JPG, JPEG, BMP, PNG, TIFF or other formats. It can also batch process URLs from a text file and automatically parse a large number of sites but it isn't free.
Update: Pearl Crescent Page Saver, a Firefox screen capture extension, also lets you save an image of an entire web page from the command line, use the -savepng flag. For example:
firefox -savepng http://www.web-screen-capture.com/
Images captured using the -savepng command line flag are saved to Firefox's Download Folder. You can set this location from the Downloads section of the Firefox Options window.