For those who may be unaware, there are easy (and legitimate!) ways to obtain extra Golden Keys for the loot chest in Sanctuary!
Go here shift.gearboxsoftware.com/home to the website, and register an account - only takes a few moments of your time. This is a service that Gearbox uses specifically for handing out extras to its players. After linking your account (for 360, you register online and then enter your data into the Extras > Shift menu), you get 2 more keys automatically!
For even more fun, follow Randy Pitchford, a Gearbox lead, on Twitter, at twitter.com/duvalmagic! Every so often, he gives out SHIFT codes that are good for several hours. SHIFT codes work once for each gaming profile, so everyone can use one whenever they're posted! In fact, there are a few active as of this posting!