is currently having a BOGO 50% off sale on select LEGO items. Not all LEGO is included. So far, I've noticed that most of the Architecture series qualifies, as well as some Creator, some Games, Books (including the Brickmaster books), and other odds and ends. Do a search for "LEGO" and look for the "Kids Sale Buy 1 Get 1 50% off" graphic next to the item in your search results. WIth free shipping on orders over $25, you're bound to find something worthwhile. Offer is good once per customer per billing address and expires at 11:59pm October 6 Pacific Time. Choose wisely and good luck.
Update: BlueDragonZ provided a complete list
of sets that are eligible for the BOGO discount.