Maybe instead of tipping offer them a soda or other form of beverage? My mom used to offer deilvery guys beer and they seemed to enjoy that.

What she said.

I've found a lot of the guys working for NPOs can't take tips. Because it is obscenely hot here and moving stuff from downstairs and out to a truck isn't easy, I'll try and have a few bottles of cold PowerAde and/or water to offer for them. I'll offer beer if I have any.

[on preview, what LunaticFringe said]

Thanks, all. I was going to offer them something to drink anyway, but I wasn't sure if that was enough. Sounds like it is!

I don't know why there is a distinction, but I feel it's necessary to tip the movers when they're moving your personal belongings from one house to another, but I don't feel it's necessary to tip the guys picking up donated furniture.

With drinks and movers:

Offer lemonade before and during the move, beer afterwards. Offer to put one on ice for the driver to carry home so he's not DUI.

I'm with mullacc on the tip ettiquette.

I'm always surprised when people suggest offering beer to working people. I mean, every place I have ever worked has a policy against consuming alcohol while at work, and I can't imagine many places are in favour of it! Also, offering delivery people booze seems especially odd, given that there is a good chance they are driving.

Anyway, honestly, I am not a prude, I swear! It just surprises me how many people suggest giving people booze. I also do like birdherder and make sure I have cold drinks on hand.

When I first started working at a large bank, I was given so much alcohol by the company that I wasn't sure if I was going to be able to work there for more than a few months. It turns out, that it just comes around during recruiting time. But, I've had plenty of beer and wine at company events since - usually after work cocktail hour stuff, but still provided by our in-house catering and on company property.