Yesterday Google announced that they've added the option to put 'callouts' on your PPC ads - something that can be quite cool and set your ads apart from the others. Offering free shipping or perhaps a promo code? As long as it's within their guidelines, you can do it.
There's something similar to this with the Google Shopping program - called Promotions. You can add a callout to your shopping ads, but these are a little more strict, usually requiring a promo code.
These new callouts are great while they're new - not many advertisers will implement them quickly, so if you do, you'll probably stand out a little bit more!