Recently I was reviewing a web site that was still evolving and wanted to mark it up and feed my comments back to the creator. (He is a friend of mine so I wasn't just taking pot shots at him!)
I wanted something to capture the entire page (most required you to scroll to see it all) and then be able to annotate it.
I found nirsoft.net's SiteShoter but that was really too simplistic and didn't allow me to annotate.
Then I found aviary.com.
In some aspects it is simplistic as well. For example, to capture a page, just put "aviary.com/" in front of the URL, e.g. "aviary.com/http://google.com"
Then you get a Flash page up with the target web page captured. There are some simple editing/annotating tools there and the option to save it to your desktop or to their site.
The editing capabilities here are simple (that's what I was looking for) to the point of being rudimentary. But be careful of clicking on any of the more advanced options. Let's just say they go to the other end of the scale. They were way more complicated than I needed.
Play with it some before you're trying to use it for real. Find your own sweet spot for the level of complexity you need and can handle.