This is just what I would do, not saying it's right. If the delivery person is super helpful and goes well out of their way and is on time, etc, I might tip $20-30. If pretty standard, but nice an helpful, $10-20. If they just show up and say "the stuff is in the truck", maybe $5-10 or no tip. I personally don't think it should be a percentage like at a restaurant.

Ok, I'll duck now. <img src="http://www.traveltalkonline.com/forums/images/graemlins/Wink.gif" alt="" />