paper and plastic.
paper takes more energy to make, but is recyclable and easily biodegradable. and typically i can get out of a store with fewer of them than plastic bags and my groceries don't end up scattered all over the back of my forester.
plastic takes little energy, and i've heard they're recyclable to some extent, though i'm not sure how widespread the ability to recycle plastic bags is. thy're also easily reused for numerous other applications (garbage bags, lunch bags, pooper scoopers, etc). i actually still use the bag i got from the apple store three months ago as a backup tucked away in my messenger bag i take to work (for lunch and/or leftovers to take home).
processes to make both are pretty dirty.
i'm really considering buying a couple/few cloth tote bags for all my shopping.
o.t... i'm trying to lay off pizza. and i used to drive for dominos when i was in college, and i don't think we ever sent something out that was anywhere near an hour late, much less two.
ask them for some coupons on top of the free pizza (preferably to another pizza place, something that actually tastes like pizza.
)