Today is the last day for Nintendo 3DS users to sign up as a 3DS Ambassador to qualify for 20 free games.
From Nintendo:
Today (Aug. 11) is the last day for current Nintendo 3DS owners to register for the Nintendo 3DS Ambassador program. Just connect your Nintendo 3DS to the Nintendo eShop by 11:59 p.m. Eastern time to receive 20 free downloadable games.
The offer is due to the recent price slash of the 3DS.