I think what you are looking for is something like
WebGrabber. It doesn't grab "through" Safari or any other browser, it just grabs most everything from a site straight from an HTTP connection.
It is a 0.7 release (from 2002), but it works. I have had issues with graphics... evaporating (leaving 0 k place holders), but I fix it by moving the site to another part of the disk (or on to a disk image).
In the end you end up with all the HTML, graphics and directory structure of the site you wanted. I have archived sites that I knew would someday disappear from the internet.
As for some of the "legal" issues brought up here, once on the internet for public view, it is fine to down load sites... infact, that is EXACTLY what web browsers are doing. No browser "views" a site on the server, it downloads the information to your system to display the pages. This app is not doing anything different... other than not displaying the downloaded pages. And you have the same access privileges you would (or wouldn't) have in a browser.
At any rate, it is a useful tool from a long time Mac OS X (and Rhapsody) developer who I think now works at Apple as I recall).