Being somewhat involved with discusions on graphics plugins for the N64 and inserting texture packs.  This is a PITA, mostly because most texture packs end up grossly disorganized and messy.  A quick example would be duke nukem zero hour.  This game ends up dumping over roughly 2000 files in a single directory.  Very messy to sort through and find out which file is what texture.
I wrote a plugin for PSX emulation before, it stunk but I did get it working (soft plugin mind you) to show proper 24 bit color and just starting textures.

How hirez texturing works is it generates a CRC or MD5 check value for when a texture is USED in game. (Jabo's PJ64 beta plugin does this at a different time I should ask how he does it.)  For the playstation no one has implemented this due to indexed images and the texture palette system. (I think it's doable Pete didn't seem thrilled .)  What this means for PS1 games is substituting a hirez texture is extremely difficult to get right.  It is possible just difficult.  Games that could use it off the top of my head are, MGS1 FF7 FF8 and FF9. Though the later looks incredibly good without it using PC resolution graphics.

Hacking the game itself to improve the graphics will put you in the same situation as the original programers, SPACE is the issue here.  I suppose for the N64 it might be possible to alter the PJ64 source (1.6.xxx) to allow for larger ROM images or a form of bank switched ROM image to extend memory space beyond the 64M limit.  The N64 maps the ROM memory much differently than the SNES and NES (it appears to be synchronize ROM memory like SDRAM is in in the PC).  In that respect the original games MIGHT be hackable to improve the graphics and or detail of a game.  Unfortunately the original game machine won't be able to take advantage of virtual hardware and these ROMs

Cyb

Well I am not going to take the time to look through all the ideals today instead I will tell some ideals of my own and read yours later,

For smb1 a naked princess hack and the same for smb2 and maybe even naked toadstool too for both games.
For Zelda 1 how about zombies ate me brains and if you don't bring back the virgin goddess that Gannon stole they will eat your brain too,
Instead of (it's a secret to everyone) it could read (zombies ate me brains).
Well anything like that would be cool you know like an howlween edition only not for kiddies,
And the scarier the better I would like it. 

For Anygame an hack where the soul perpose is to kill osama, and stomp on his corpse afterward or something more painfull like torturing him to death then kicking the shit out of him afterwards to take out the anger of our fellow dead American's on his freaking ass and scare him out of hidding for fear of what might happen to him if he continues to hide out and piss us off further. well maybe thats to elaborate but any game where you could kill him would be cool. Yes I know that there's osama hunt but thats only one game. 

Sorry I forgot about Mystic Quest for Snes my bother always ask me why nobody has made a hack of it, and as far as I know it's the only game of it's type for the snes, I am aware of the monster editor for it but I think it's over my head. so any hack of it would be cool.

These are just ideals altho they may sound like request. 

Well Thats all I can think of right now. I will get to reading now.

Sorry I had to edit this again.

Any more crazy ideas for romhacks?

Well, somebody linked a little while back to a page of SMB romhacks.
One of them was SMB314, which was SMB3 World 1-4, recreated in SMB1.

Kinda of intersting, but I thought maybe somebody created the first romhack centered on pi.
If someone did that, it was probably be the nerdiest hack ever done.

Well, one crazy idea I'd like to see would be a hack of River City Ransom that either adds new moves, or at least makes it so that certain existing moves (like Fatal Steps) are actually worth buying, but I'm not holding my breath on that.

What about templates?

Like, from what I have seen in my time here and Acmlm and from what I have heard among my friends, it seems that people who want to do hard core hacking start off with Final Fantasy. But what if we made it easier for the weekend warrior variety by making specific genres of hacks for FF alone. For instance, making a western template would involve a gunman, a (bar)wench, a lady(of the night), an indian, a doctor and a chinaman. And no, none of this is meant to be racist or anything, but I'm going with your age old western genre. Swords are made into guns, heavy swords (the kinds only fighters and knights and red wizards can use) become rifles. Knives and axes change just enough to be like knives and tomahawks, and we can just take out stuff like hammers and those things to put in whips and whatnot.

And there could be a Samurai template. A Ronin, bandit, monk, ninja... etc. All the monsters can be from Japanese lore, and become stronger all the way up until like... I dunno a whole lot about Japanese lore, but you get the idea.

Atlantian, were you're mostly the same adventure, except that the cities or towns could be across depths that a Merperson can't swim on their own, things like that.

Cyberpunk, like making it so that more items (computers) lead into dungeons where you need to jack in to go online and whatever.

Hell, alien invasion, ninjas, pirates (that one would be fun, I bet you.) Caturday, the internet. I bet any game on the planet could be made out of FF. I had a thought for the internet one. The enemies could be a series of memes, ending with the all powerful Longcat, and the super powerful sword can instead be Tacgnol, and so on and so forth.

Yeah. Except not the same game... I've never played Live A Live on my own, so I haven't got a clue aside from what I've seen on RPG shrines.

One of them wouldn't happen to start with Tub, would it?

G... G... Goa...OH! I gotcha. Ew...