One small thing that many people can do to reduce waste is to switch from paper or plastic grocery bags to reusable bags. This is becoming more and more popular - even Wal-Mart sells reusable grocery bags now. There are a few things that make people hesitant to use them, and I will address them here.
Reusable grocery bags are too expensive.
This is an outright fallacy. You don't need anything special - even a plain canvas tote you find at Goodwill would work perfectly. Wal-Mart sells their bags for $1 each. When considering how many you need to buy, do not consider how many plastic bags you use. In my experience, baggers always use far more bags than really necessary. Even when shopping once every week or so for two people, three bags is enough for me. Because many of the reusable bags you can buy now in grocery stores have a flat bottom, you can fit more inside anyway. My grocery store even gives a small incentive to bring your own bags - 5 cents per bag.
It isn't that important to use reusable grocery bags.
According to National Geographic, between 500 billion and 1 trillion plastic grocery bags are used worldwide each year. Millions end up as litter, and take "months to hundreds of years" to disintegrate, all the while sending toxic bits into our "soils, lakes, rivers, and oceans." That isn't including the amount that end up in landfills. While plastic is a better choice over paper in terms of energy consumed to produce them, the amount of time it takes for them to disintegrate is astounding. If you aren't at least going to reuse them for something else, don't just throw them away - many places, including Wal-Mart and some grocery store chains such as Hy-Vee, have grocery bag recycling drop-offs. Your great-great-great grandchildren will appreciate it.
It's inconvenient to use reusable grocery bags.
While I do have a few larger bags that I hang on the doorknob so I don't forget them, there are also very compact bags being produced currently, such as ChicoBag. I have one in my purse. They also have a clip so you can hang them from your belt loop or keychain. These are made specifically so you CAN'T forget them. They just hide in your purse or pocket until needed. That isn't the only brand, either - there are many companies who focus on creating compact reusable bags.
I use paper and plastic grocery bags for lunches/trash liners/to clean up after kitty/etc.
This is a harder concern to tackle - one that I am struggling with myself currently. If you bring a lunch in a plastic bag, pony up the $5 for a lunch box. If you use them as trash liners, consider what you are throwing in them - are you throwing food or anything that can rot in them? If not, you don't really need a trash liner. You can just empty the garbage into your kitchen trash. If you are - why not take the few extra steps and throw away your food in the kitchen anyway? Much of this comes down to convenience - how far do you want to go? Actually walking to the kitchen isn't THAT difficult. In terms of cleaning up after pets, I'm not sure where to go yet. There are some flushable brands of cat litter, although that isn't always an option for people. If you own a dog, you can begin a compost pile. If anyone has any ideas, feel free to leave them here.
I will end with a few links to helpful places:
If you live in Minnesota: http://www.reduce.org/bags
Now when they ask you "Paper or plastic?", you can say, "Neither!"