Enjoy!!!! (please post if you take them so everyone knows they're used, thanks!)
The Binding of Isaac + Wrath of the Lamb DLC Steam Key = B09QM-YL8CJ-0ARY6
Cave Story+ Steam Key = ILPW4-53IGV-HRCCQ
Yes, mine was USPS.
Not related to the charity, or even this thread specifically, is there a setting on CAG to receive emails on thread updates? I've been looking but haven't found it. Do you need to be the thread creator?