Local Website Archive is a useful utility that allows you to download web pages to your local hard drive. While this can be accomplished via the "save page" option in most browsers, Local Website Archive Lite (free) offers enough additional features and functionality that it's well worth installing.
While it's possible to use Local Website Archive Lite without browser integration (by entering an URL directly), it's really most useful when it's part of the browsing experience. Depending on the browser, this will be a right-click option, a button, or both. If you see a page you will want to save (for example, recipes, a list of cheat codes for a game, or a long article you'd rather read offline), you activate Local Website Archive Lite and go through a three-step wizard to save it. This latter bit can be sometimes annoying and is one of the program's few, albeit minor, flaws, in that using it can break the 'flow' of your work slightly.
The advantages of using Local Website Archive Lite over just "saving a page" are that it places all of your saved information in a single, easily accessible place, and allows you to categorize the saved pages in folders. Saving pages one-by-one can lead to a clutter of images, html, CSS, and so on. Further, Local Website Archive allows you to save PDF documents, and thus can aid in creating an organized library of them--useful for things like documentation, in my experience.
Further, Local Website Archive has search feature, which can make it easy to extract or locate data within a collection of saved pages, on the level of a single file, a folder, or a hierarchy of folders. Unfortunately, it lacks some refinements such as case sensitivity or searching for a whole word only.. looking for "die" will return documents containing "diet" or "diecast," for example.
The Lite edition of Local Website Archive is functional enough that I've used it for a long time without feeling limited. The 30¬ Pro version offers features such as queuing pages for saving, among other things.
At a price of nothing, I strongly recommend Local Website Archive Lite if you save Web pages even occasionally.