I'm a huge fan of reusable shopping bags. They're much easier to carry than the standard "paper or plastic" variety; reusable bags are sturdier, have easy-to-grab handles, and boast twice the carrying capacity.
Besides that, they're reusable--and often made from post-consumer recycled materials. That's a plus for the environment.
Sometimes, these bags even offer a plus for your wallet. Many stores offer perks to shoppers who bring their own "green bags"--financial perks. Target, for example, takes 5 cents off at the register for each reusable bag you use for your purchase. CVS's rebate program requires you to purchase a "green bag tag" that you can hang on the reusable tote of your choice. The cashier will scan this tag each time you shop, and after four trips you'll receive a coupon for $1 off your next purchase. The 99-cent "green bag tag" at CVS pays for itself in only four visits.
I do most of my grocery shopping at ShopRite, and since I use 8 to 10 green bags on each weekly trip, I save 40 to 50 cents a week just by remembering to bring my own totes. I've gotten quite a few free bags through store promotions, so I figure that I recouped my initial $5 investment in green bags in under three months.
The scuttlebutt now, though, is that many retailers are abandoning the green-bag rebate programs. They don't think the rebate makes a difference in whether shoppers remember to bring back their reusable totes. In fact, some communities have banned plastic shopping bags or begun charging a tax on each one used.
I hope ShopRite doesn't hear about this. And I hope New Jersey doesn't start in with the ban or tax idea; I need the occasional plastic bag as a wastebasket liner, and paper bags still make the best book covers. I'm reusing them either way--sounds green to me!