Google has made another change to the AdSense referral program--this time, tied to the location of a new client. Now, publishers can receive referral credits regardless of where they're located--provided the new AdSense clients they refer come from North America, Latin America or Japan. Referrals that come from any other country will not be rewarded--and yes, this includes the U.K. The giant also decreased the referral credit for getting users to pick up Google Pack and Firefox from $2 to $1. The modifications were framed as part of the continual evaluation process of the referral programs to ensure that they remain "effective and sustainable."