I tip my van drivers unless they are rude, dangerous, or some weird reason. If I have to wait that doesn't change the tip, mainly because sometimes it isn't their fault and at the end of the day it's just a buck.
However, tipping has gotten absurd. The other day I bought a cup of coffee, $2. She handed me an empty cup and pointed towards where I could fill it up. There was a tip jar and a spot to tip on the receipt. Yeah, I'm not tipping there. I bought a 2 donuts a few months back, she handed me the slip to sign and said "don't forget to tip". What the hell is going on, you handed me two donuts which were within an arms length from where you are. If we're tipping for that I should get tipped for handing you back your pen and signed receipt. I don't tip for these kinds of things.
As someone else said, I tip wait staff, van drivers, delivery drivers, and bar tenders.