In addition to Coinstar's current promo for $10 iTunes gift card when you cash in $40+ in coins and select iTunes as your reward option, Coinstar now has a promo for Overstock. Cash in $25 or more for an Overstock.com e-cert and you'll get a 10% off coupon. This offer will run through 5/17.
Also, Coinstar has an upcoming promo for Old Navy, which they are advertising in advance of Mother's Day. The Old Navy promo doesn't start until 4/28, so the info isn't on their special promos tab just yet. However, after 4/28, you can dump in $10 or more in change and select a Gap Options Old Navy e-cert as your choice and you'll get a 30% off one single item coupon. Could be great to pair with sales!