So, for a gestalt campaign, using all books for D&D 3.5, I made a Psychic Warrior/Monk character. I just turned level 16, and I saw the power Rage of the Remorhaz. If I make an unarmed attack while this power is in effect, do my attacks now deal the 4d6 fire damage? It says that anyone attacking me with unarmed or natural attacks do, so I am under the impression that the opposite should also be true, but would love to confirm this before deciding on this power.
Unfortunately, an effect only does what it says it does
The description of the 6th-level psychic warrior power rage of the remorhaz [psychometabolism] (Complete Psionic 97) says, in part, that
Your skin pulses, generating a heat so intense that anything touching your body takes 4d6 points of fire damage. Creatures striking you with natural attacks or unarmed attacks are subject to this damage as well. Creatures striking with melee weapons do not take damage from your heat, but their weapons do take damage.
…And, sadly, that's pretty much the extent of the power.
The power neither causes everything the psychic warrior touches with his body to be dealt 4d6 points of fire damage nor causes the psychic warrior's own unarmed or natural attacks to deal an extra 4d6 points of fire damage.
For comparison, many spells and effects endanger foes that harm (or seek to harm) the user yet the user gains only minor benefits from such effects if no foes do—for example, the 1st-level Sor/Wiz spell babau slime [trans] (Spell Compendium 22), the 4th-level Sor/Wiz spell fire shield [evoc] (Player's Handbook 230-1), the 7th-level Sor/Wiz spell acid sheath [conj] (Spell Compendium 7), and the soulmeld mantle of flame (Magic of Incarnum 78) (although when bound to the shoulders chakra the mantle can be used offensively) are all based on foes striking (and, typically, also dealing damage) to the user in much the same way the rage power is. None of these similar effects allow the user to deal extra damage with the user's attacks, either—the effects don't say they do, so they don't.
This does make the rage of the remorhaz power as written pretty disappointing, though. I'd suggest that if you're seriously considering the power for your gestalt monk 16/psychic warrior 16 that you ask the DM to house rule the power to work like you want it to work. I can't know if in your campaign this would be balanced, but considering what you could have picked to play instead of a monk/psychic warrior, this—in the abstract, anyway—seems okay.
I would say no.
The text of the power is not explicit in this regard, but it is conspicuously explicit in another regard that is RELEVANT to determining this ruling.
"anything touching your body takes 4d6 points of fire damage"
"Creatures striking you with natural attacks or unarmed attacks are subject to this damage as well"
Taken together, it is obvious that the authors of this feat felt that "creatures striking you" was not covered by "anything touch your body". There is no practical difference between that and "you striking creatures", and thus, I believe that the authors would have explicitly called out that interaction, had that interaction been intended.