Gamefly cuts 20% off select game preorders for Windows via coupon code "MAR20OFF", as listed below. That beats Amazon's price for each game, even when you factor in the $5 credit they're including with their deals. The games, with prices after coupon, and release dates noted:

Plants vs Zombies: Garden Warfare for PC for $23.99 (low by $6; released 6/30)

The Elder Scrolls Online for PC/Mac for $47.99 (low by $12; released 4/4)

The Elder Scrolls Online: Imperial Edition for PC/Mac (pictured) for $63.99 (low by $16; released 4/4)