If you consider yourself a LEGO builder, you most likely know what Bricklink is. Otherwise, your first question is: what is it, and why should I care?
Bricklink is an unofficial marketplace for anything related to LEGO including sets and bricks. If you look at any creation on the net, chances are that it contains a significant amount of bricks purchased via Bricklink.
Just a two for this week:
(via The Lego Car Blog)