Gearbox Software offers SHiFT Codes that unlock Golden Keys for use on the PlayStation 3, Xbox 360, PC, or Mac versions of Borderlands 2 for free. That's tied with our mention from two days ago of a similar offer as the best such deal we've seen. Each Golden Key allows you to access in-game items. The codes:

• PlayStation 3: W3CTB-WJKT3-ZZT9W-SSC53-H3KJT-5XX9H
• Xbox 360: KTWJJ-JXJK3-SXH3R-56JBT-BZC9W
• Windows / Mac: CJWTB-FF9KX-K3H33-TJJ33-JJHTH