Our favorite LBS gives us ~15% off. We don't know quite why. We never asked for it. We aren't big spenders there, although I bought a bike there a year ago that they had heavily discounted to move off the floor. They wanted to give us the water bottle cages for that bike, but my SO tried to pay for them because he knew they weren't making much profit off the bike.

I have also occasionally sent folks there to look at the bikes and maybe buy one.

My SO wanted to buy a PI vest from the clearance rack and they just gave it to him: Happy Birthday!

Sometimes we bring them a six pack of Fat Tire Ale.