Distributing Gift Cards to the public is really quite easy.
You can leave them with your tip at a restaurant. Coffee houses, gas stations, grocery stores, just about anywhere you may go, you can hand out a gift card. Banks, Post Office, if you have a local business, you can ask them to hand them out.
We have a small natural food store in our town and they'll hand them out. Be imaginative, think outside the box and your distribution will be endless.