It Pays to Use Google Toolbar on Firefox
“Mozilla Firefox fans can list plenty of reasons they chose that browser over Microsoft's Internet Explorer. The latest could be that they got paid to.
Google recently expanded its AdSense for publishers programs to include referrals to both its Adsense program and Firefox with Google Toolbar. The new Firefox referral will pay AdSense publishers up to $1 "per referral the first time a user installs Firefox."