The link below will show you the 29 used games currently available on Walmart.com. Although the selection is incredibly weak right now, I'm going to make a safe bet and say that the selection is going to grow larger pretty soon. Hopefully, the prices will become more competitive as well.
UPDATE: All used games have been pulled from the site.
UPDATE #2: Pre-owned landing page added with 221 games for sale.
Used Game Selection at Walmart.com
Edited by CheapyD, 20 September 2009 - 02:43 PM.