Until August 31, you can get 10% off select HDTVs purchased at Amazon.com when you use your Amex card and the promo code AMEXTV10 at checkout. There are a lot of TVs available, so make sure to click through your favorite brand (or click "all") to see what's available.
In addition to this, there are some other promotions going on. Some TV's are already discounted, and some 3D TV's come with free 3D glasses.
If I had to give some LED-LCD recommendations, I'd say look at the Vizio XVT3D474sv (+2 pair glasses) or the LG 47LW5600 (+14 pair glasses).