What are the pitfalls to driving Web site traffic with online discounts? For starters, losing money. If the campaign catches on through Facebook, Twitter and other social tools, it can quickly turn a small promotion into a major ordeal. Kevin Gibbons serves up tips on voucher codes, mailing lists, gating the Facebook campaigns, improving organic traffic, and more. Publishing discount vouchers on a Web site also will encourage inbound links, boosting its presence in the search engines and building customer loyalty.