A handy-dandy list of LEGO®-related websites
Brickset – the largest online resource for new & used LEGO® parts, sets, and more.
Brickowl – a newer online resource for new & used LEGO® parts and sets. Smaller than Brickset but with a more modern interface.
News, Information & Set Databases:
Brickset - a leading online resource for LEGO® collectors worldwide. Includes a blog with info on upcoming sets, reviews, and other info, as well as a database of nearly every LEGO® set ever made. You can keep track of your LEGO® collection with their database tools. Also a nice LEGO® glossary.
Eurobricks – A European blog with info on upcoming sets, set reviews, and more.
FBTB – Another excellent blog with lots of LEGO® info, with a Star Wars focus.
Brickipedia – a LEGO® wiki with all kinds of info.
Brothers Brick - Excellent blog about MOCs (My Own Creations).
Brickshelf - User submitted galleries of MOCs, events, and other LEGO® stuff.
MOCpages – Share your MOCs and view what others have created.
Rebrickable - Shows you which LEGO® sets you can build from the sets and parts you already own. You can choose from official LEGO® sets or custom made MOCs (My Own Creations) by many different designers.
Didier Enjary’s The Unofficial LEGO® Advanced Building Techniques Guide (PDF document, from 2007 so lots of newer parts are not included, but very handy!).
The New Elementary – Blog highlighting new LEGO® parts and their uses.
The BrickBlogger – Includes guides to various techniques as well as info on new sets and more.