By DarKnight13

Fireballs
Movement and Combustion:
Offset $63E2(tsv) $61E2(ntsv)
1C - normal
1B - explode on contact with anything (except Mario)
19 - appear in the air and just bounce along the top of the sky
15 - straight forward
13 - same but bounces off the corners of blocks every now and again.
10 - explode on contact but don't hurt anything
FF - explode on Mario (hehe) but don't hurt him
CF - kill first enemy on the screen when you shoot a fireball regardless on whether or not you actually hit it
9F - shoot a fireball then jump to launch into the air; jump and shoot a fireball in the air to either shoot up or shoot down (sometimes through floor)

Height and Angle:
Offset $63FB(tsv) $61FB(ntsv)
F8 - normal
D0 - 2 blocks above Mario
CA - 3 blocks above Mario
FE - shoot slightly farther
FC - shoot much farther
F7 - straight ahead; misses goombas but sometimes hits koopa troopas

Mushrooms, Goombas, and Koopa Troopas, Oh My!
Properties:
Offset $6206(tsv) $6006(ntsv)
03 - normal
E0 - everything that touches ground bounces
E1 - everything that would bounce in E0 falls and some things walk through walls.
E6 - you can't stomp anything but you bounce off ie. goombas flatten then pop back up
FF - everything falls through the floor
17 - everything is bouncing around and giving you lots of points.
38 - 17 without the points
39 - enemies bounce after you
3B - everything bounces until it hits the lowest ground (cracked blocks) then it is carried away and can't hurt you.
42 - most things are scared and bounce away!
43 - most things are scared and run away even through bricks; jump off cliffs and then bounce if they land on ground
4D - 43 with less bounce
54 - everything runs VERY quickly your way through anything but doesn't turn around
56 - everything runs quickly your way through anything but does not turn around

Stomp Reaction:
Offset $5BE5(tsv) $59E5(ntsv)
04 - normal
89 - walk flat (can still hurt you)
49 - small spring
29 - fall left
69 - fall right
09 - flatten then unflatten while falling
Offset $5A95(tsv) $5995(ntsv)
01 - fall down
49 - traffikoopa (morph to turtle; keep stomping to change to red, then green, then red, ect.)
Offset $5AE2(tsv) $59E2(ntsv)
00 - don't flatten but turn around
01 - unflatten quickly (can bounce off of multiple times to get 1ups)
02 - unflatten quickly (no multi-bounce)
30 - disappear in 30 seconds
FF - stay flat and don't disappear

Jumps
Note: The lower the value, the higher the jumps. Experiment!
Standing:
Offset $3634(tsv) $3434(ntsv)
20 - normal
19 - Luigi jumps
00 - float up as long as you hold the button
I'm not sure what the next byte means but set it to whatever you put standing jumps as.
Walking:
Offset $3636(tsv) $3436(ntsv)
1E - Normal
19 - Luigi jumps
00 - float up as long as you hold the button.
I'm not sure what the next byte means but set it to whatever you put the running jumps as
Running: Offset $3638(tsv) $3438(ntsv)
28 - Normal
21 - Luigi jumps
00 - float up as long as you hold the button.

Fun With Warp Zones
Note: Some values can give you strange but fun worlds. I'm not entirely sure how it works so you'll have to be a bit more careful here.
Offset $0A02(tsv) $0802(ntsv)
Warp Zone 1
You'll notice three values on an unchanged ROM: 040302. If you picked up on it, these are the hex for the 4, 3, and 2 on the warp zone levels! Seems innocent enough? Nope! You can really screw up the warps zones with this! Try changing those values to anything at all! You can make a warp to the minus world (24 is a space, so it looks like just a minus) or to any other world with just a change of the hex value! Be warned: you can make plenty of screwball worlds with this!
Offset $0A06(tsv) $0806(ntsv)
Warp Zone 2
Offset $0A0A(tsv) $080A(ntsv)
Warp Zone 3

My Theory About the Minus World
For a better understanding about this you should read the hacking info about warp zones. We all know the little trick to get into the minus world, that infamous water level that goes on ad infinitum. You may not know the Science behind it, however. There are three pipes in the 1-2 Warp Zone. Those pipes were meant to be used by the first warp zone level selector. However, for reasons unknown, the little block trick loads the SECOND warp zone selector instead. That very warp zone set was meant for a warp zone with only a pipe in the middle! What about the other 2 pipes? They're there but they use the space so it looks like nothing has changed! Veeeeery sneaky of Nintendo! When there is a pipe under the "warp to number" (?), it goes to world ?-1. The "warp to number" is " " instead of a number like expected so it goes to " -1" which we just interpret as "-1", ignoring that little monster that gets us stuck in the endless pond. THAT, my friends, is reason for the minus world. It was an accident, really!

Please note I'm not responsible if any of this screws up your ROM it's up to you to back it up. I haven't listed all the possiblilities her so feel free to explore. Some things work differently in conjunction with other stuff. If something is wrong it's because of that. If you find anything good that I don't have here send them to me at darknight13@home.com. Some other things I would be especially grateful if people discovered are the speed if Mario, the movement properties of the Hammer Brothers' hammers, and the effects of mushrooms, stars, and fire flowers.