Select "Extras" at the main menu, then the "Preorder" option. Enter one of the following codes to activate the corresponding cheat function.
360152 - Sora Katana of the Katakara Clan
360378 - The Lost Blade of the Kusagari Clan
58855558 - Nihonto Hana Sword
3582880 - Barracuda
370402 - .357 Magnum, The Tataro
Easy Money
As soon as you learn "The Dragon" (in Rattlesnake Canyon) your money troubles are over. Kill all but one enemy in a pack. Use The Dragon to slam him against a wall for 500 dollars -- you can repeat this for essentially infinite cash.