I believe a good mod would be a narwhal mod where there were narwhals with the same spawn settings as squids except you can craft a water saddle that when put on a narwhal lets you (a) ride the narwhal and (b) breathe underwater as you ride.

Recipe for a Water Saddle:

w l w
i

w= water bucket

l=leather

i=iron ingot

There would also be a new boss called Stefano which is summoned in the nether whenever you place a golden star in the nether.

Recipe for Golden Star:

g
g n g
g

g=Gold Ingot
n=Nether Star

Stefano is a statue which appears to be pure gold which holds a diamond sword. He is 3 blocks high and has 10 hearts. He is unaffected by fire, lava, hostile, passive, and tameable mobs (This does not include Iron and Snow Golems). Strangely snowballs will take out 3 hearts making snow golems the key to their defeat. Stefano will drop 9 gold blocks or 3 diamond swords.

Finally I introduce the last part of the mod being hippies. Hippies are neutral mobs with behaviors like zombie-pigmen. They are found in all areas of the overworld except jungles, deserts, and any Snow or Ice biome. Hippies only attack is punching making it very easy to kill them with a bow. Hippies will drop Peace Sign Medallions. Peace Sign Medallions can be used along with spider eye to make a Spider Medallion.

Spider Medallion Recipe
p p p
p s p
p p p

p=Peace Sign Medallion
s=Spider Eye

The Spider Medallion can be used on spiders to make them neutral to you unless you attack afterwards. They can also be used to put hippies in a hypnotic state for 5 minutes allowing you to easily kill them without return fire.

This would help the people who find Jeb's work on Minecraft is not so much about expanding how much there is to do in-game. It would also help people to experience a minecraft experience unlike ever before, plus the Stefano boss is pretty epic! If you are a modder without any ideas put me in your Additional Credit when you make the mod!

This is my idea for a minecraft mod so I hope you like it!