We've celebrated b-days at The Ram (a micro brewery with several locations) They always give us a free dessert, the Mile High Choc Pie, when we tell them we have a b-day. they've never once asked for proof or ID. (We don't abuse it though.) Kids can sign up to be in the kids club and you can go online and sign up for emails and you get coupons from time to time. We've gotten Mother's Day and b-day discounts.
I've found that a lot of the b-day treats have gone away. Most places don't do free dessert like they used to. Golden Corral used to do a whole dinner for free, now it's just a drink. They still do the Veteran's Appreciation dinner for free in Nov though and you have to have proof of service to get it.