From Oriental Adventures...
Furious weapon increases your rage abilities by 2.
*polite cough*
Mantle of Rage (
Online, 4,000gp) grants you the ability to Rage as a 1st level Barbarian. It's important to note that the Mantle it's self doesn't directly grant Rage usage nor does it have charges, as it says it gives you access to a Class Feature as X level Class. Meaning once you've used it, you can pass it to your buddy and they can use it to enter Rage as well. Couple this with a +1 Furious Gauntlet (8,302gp) and potentially everyone in your party can access Greater Rage once per day.
And don't forget Lord of Darkness has Rhul, aka "Battlewine" (a checmial listed in a side bar in another book, forgot which). For 50gp you obtain a +4 Alchemical Bonus to Str/Con and -2 AC for one minute. Additionally, unlike Rage, a DC 16 Will Save lets you choose to do whatever the heck you want (cast a spell, use a wand, fire a bow, etc). And finally, it is Alchemical Bonuses so they stack with Rage. So good news to the Barbarian I guess, but imho better news to the party that replaced the Barbarian with someone useful. Instant Hulk mode, in a jar.