This week's tool: the Scrap Book extension for FireFox .
Scrap Book is a combination of "save this web page" and an organizer for saved web pages. It captures exactly the state of the web page as currently displayed to a disk cache and provides a FireFox side-bar to browse or search your saved pages.
To view a page again you can click on it and you'll see it exactly as you did the first time and with no further server interaction. (Of course, there's no guarantee that links to your shopping cart will still be valid -- that's entirely up to the server.)
It organizes your saved pages in a standard tree view, allows you many different kinds of search (including regular expression) and is generally just very useful.
My most common use is to save order or recept pages (you know, the kind that say "print this out for your records? Yeah, right, like I'm going to print it out...)
I also use the folders to track what I've got on order vs. what I've received, reimbursible expenses, agreements and licenses, etc, etc.