Just to be up front, I get nothing from this company for posting this. I do a lot of mailing of packages, especially at Christmas time (the joys of living 13 hours away from the closest family), and I'd been on the hunt for a cheaper source of packaging supplies than Staples, Officemax, and Walmart. I found Papermart.com: http://www.papermart.com/HOME . They have boxes, envelopes, cans, wrapping paper, tape, etc. etc. etc. If you don't mind buying in bulk for some things like tape, it's a good spot. You can buy in smaller amounts for a lot of items.
There are some cute bags and containers that I thought would be nice for the cookie zerg, so I thought I'd post the link so people can get their shipping supplies in time for December.