I have just contacted gamestop over the $10 off future purchase codes that were give out around May/June of this year. These codes were received from ordering games such as New Super Mario Bros.
Here is a link to CheapyD's original post about these...
I hate that the power hour deals look and see if you have purchased the game before and will not let you buy a new copy even if you purchased one months ago.
PS3
Lost Planet 1- 6.50 base
Rock Band AC/DC Track Pack- 3.25 base
Lego Rock Band- 6.50 base
Elder Scrolls IV Oblivion- 5.00 base
Wii
New Super Mario Bros.- 25.00 base