I haven't tried this, but apparently people have found a glitch in EA's 'buy one game, get another free' promo (black friday?).
Games:
Game

Regular Price
Mirror's Edge

$9.99
Command & Conquer 4 Tiberian Twilight

$19.99
Mass Effect 2

$19.99
Battlefield: Bad Company 2

$19.99
Medal of Honor Digital Deluxe Edition

$52.98
Dragon Age II

$79.99
DARKSPORE

$39.99
The Sims Medieval Special Edition

$79.99
Battlefield 2: Complete Collection

$14.99
SPORE

$49.99

Apparently you add them to your cart, then remove the one with a cost, then re-add it and your total should be $0.00.
Dunno if they'll honour all of it, but I guess you could give it a shot.

Details: http://www.ozbargain.com.au/node/58001 (read comments)