Go to http://excedrin.com/offer to sign up to get a coupon for a free Excedrin product (up to $5.99.) Your coupon will be delivered by mail and the website says it will arrive in 3-5 days.
I also scanned Excedrin's website and found $1 off printable coupons for Excedrin Migraine, Excedrin Express Gels, Excedrin PM, Excedrin Back & Body, and Excedrin Menstrual Complete.