I don't tip delivery people...I rarely even see them. The mailbox is at the end of our very long driveway, so I never see that person, either. Nobody really goes out of their way to deliver.
When we still had our office, we had 2 regular mail carriers and they DID go out of their way for us. They each got a tin of chocolate-covered peanut brittle from Virginia Diner at Christmas--which they loved!
DH & I have gone to the same hairstylist for 25+ years...we have kind of a different relationship with her. Her salon was right next door to our office, and I often helped her with things like her business and cosmetology license renewals (she's not real computer-savvy), making copies, etc. I would also "baby-sit" her chihuahua if she had an appointment during the work day and couldn't take the dog with her. We also helped her (though not financially) through a very difficult two years, with lots of encouragement, listening ears, and even more dog-sitting.
As thanks, she never raised the prices on us, and does her very best to accomodate us with appointments. When I was getting color and a cut, she would only charge me for the color job. We also continue to go to her salon, even though it's now a 45-mile round trip since we retired.
I would feel awkward giving her a gift or tip at this point! We did, however, start paying her a little more, though not at her request. In fact, she tried to talk us out of it!