This is deservedly the most famous and popular book on homebrewing. It is simple to follow and well-written, and covers everything you need to know to brew your first beer. It's the number one best selling book for beer on Amazon. But the dirty little secret of this top-seller? The first edition is available for free on Palmer's website.
Brewtoad is a great site for those of us who are starting to make our own recipes. On top of a simple interface, crucial brew logging ability and a massive database of recipes, this site integrates all the complicated calculations homebrewers used to have to make using pencil and paper. You can choose the style you are aiming at, and the site will tell you if your beer will end up within the style guidelines. Includes bitterness, color, OG/FG and the ability to scale recipes up or down. It's free and essential.
Once you start making up your own recipes, this series of hop charts from Brew Your Own magazine is incredibly useful. There's a drop-down list to select the style you want to brew, and each chart tells you the main hops used in that style, along with good substitutions. Perfect if you prefer to shop solely at your LHBS (Local Home Brew Store/Shop), as they inevitably won't have the specific hop you thought of for your radical new craft ale. The flavor notes are actually great too, for when you're trying to imagine a flavor profile.
Undoubtedly and undeservedly a niche site, GruitAle.com is an amazing reference for those of use interested in brewing or just learning about gruit ales. A couple of years ago I brewed my first gruit ale, which was also my first ale of any variety. Now I have started a gruit garden and plan on experimenting with a series of small scale gruit brews. GruitAle.com has been an education and an inspiration.
This is the only store* on the list, and really it's a two-fer for me. Seven Bridges is both my LHBS and a national-level organic brewing supply resource. I think we should all support our LHBS. That said, you're eventually going to want something they don't have. I brew largely organic, and Seven Bridges can supply everything from organic malt extract to hops and some great organic beer kits in extract, partial and all-grain varieties.
*I'm not affiliated with Seven Bridges or any of the sites on this list.
Results from juice, yeast and sugar experiments" post in the cider section could have been a Master's degree thesis. The "Easy Partial Mash Brewing (with pics)" could replace one section of Palmer's How to Brew, but with better pictures.
Let us know in the comments if you have any hidden gems or obvious giants that could make this list (or a longer one!).