Update: There have been a couple modifications and additions to the Dragon Age: Origins cheat code pages. Now, it should be easy to activate the cheats (even on the Steam version) if you follow the instructions as written. Thanks to all the contributors.
Dragon Age: Origins pc cheat codes are here. They aren't exactly the easiest codes to activate, but they are worth the time once you have them going... here are the details.
Please note: The use of cheat codes for Dragon Age: Origins requires the use of a command line parameter, and editing of a game file. As such, it is highly recommended that you first make a backup of any files before you edit them.