At the grocery store I ususally go to, I tend to gravitate toward this one cashier, a high school teenager with a winsome grin AND good eye contact. I'll get at the end of a longer line for her to ring up my groceries. I don't remember the name on her nametag, but I really appreciate her demeanor. The good eye contact was what impressed me first. When she's not there, I give other cashiers a try, thanking each one (as well as the bagger) for their service. This one girl is the only one who consistently gives good eye contact and a smile. She often asks me how I'm doing (again, with good eye contact), and occasionally will comment on something I'm purchasing to spark a short conversation, something like, "Mmm, that looks good. Have you tried it before?"
Over the weekend, I was included for dinner with George's family at Ruth's Chris Steakhouse. Several people in service roles there gave us good eye contact (as well as great service!). I would wager that good eye contact is either part of the training at Ruth's Chris, or people working with customers there already have that skill down pat. It's probably part of what got them to that level of restaurant service.
During college, I worked as a waitress, and come to think of it, I can't remember if the importance of eye contact was taught there or not. I'm sure my high school debate coach brought it up during debate class in the early 80's. I can't remember where else I learned it, perhaps from my parents, who are both great conversationalists.
After I'd been on the Rice Diet for several months, one of my coworkers at Duke and I were talking about the weight loss, and she commented that she could see my eyes better since I'd lost so much weight. That's one of the best compliments she could've given me, and she probably didn't know it!