Pokémobs

Pokémobs is a brilliant mod for all the Pokémon fans out there. It adds loads of Pokémon to the game. You can craft Pokéballs to catch them, level them up and feed them berries with different effects.
This is a mod that really has to be seen to be believed.

Download:
Pokémobs

Cobblestone Fence Mod

Cobbestone Fences is a mod that adds nice little cobblestone walls to Minecraft. It was created based on an idea by Reddit user CMDBob.
These walls look very nice and are a great addition to many builds.

Download (Requires Modloader):
Cobblestone Fences

Rei's Minimap

Rei's Minimap is another great mod for Minecraft.

It adds a small minimap to your screen. With this you can see the land around you and you can also see any players and mobs that are near you. It even has a mode for mapping caves underground.

It also has a very nice feature that lets you set a point on your map that points to where you last died.
This is very useful if you have died and need to go retrieve your items.


Download:

Rei's Minimap

Morecreeps and Weirdos

A Lollipop Man

Morecreeps and Weirdos is a mod for minecraft that adds many strange creatures and people into your game. These include prisoners, zebras, lolliman (a lollipop man), ratmen and so many more. They really have to be seen to be believed. This mod adds a bit of fun to the game with its strange and ridiculous creatures.

Download:
Morecreeps and Weirdos

MAtmos

MAtmos is a mod for minecraft that adds many new ambient sounds to the game.
This means if you are standing on top of a very high mountain, you will hear the wind whistling by. It also adds sounds for things like swinging a sword, and changing items.

Here is a video showing you an example of the sounds:
MAtmos Indroduction

Download:
MAtmos

Water Shader

Minecraft water with the Water Shader mod

Water Shader is probably my favourite mod. What it does is makes the water in minecraft look like real-life water with reflections and ripples. With this mod, the water looks like something out of a very hight budget game. I could not reccomend this mod enough.

Download:
Water Shader

Mo' Creatures

Kittens in Minecraft thanks to Mo' Creatures

Mo' Creatures is an amazing mod that adds many more animals to the game.
Theses animals include kittens, lions, horses, deer, fish, mice, dolphins, sharks, bears, werewolves and loads more. The extra animals really enhance the gameplay of minecraft and make it even more fun to play.

You can download it here:
Mo' Creatures

Singleplayer Commands

A cave with netherrack replacing stone and lapis lazuli replacing water

Singleplayer Commands is another great mod that allows you to use commands, like in multiplayer, while playing singleplayer mode. It also includes the world-editing tool WorldEdit that allows you to make large-scale changes to your world. For example you could select a large area, and then replace all stone with netherrack for your amusement. It is also very handy for large builds as you can build a huge wall in just seconds.

It is available for download here:
Single Player Commands

Zombe's Modpack

Zombe's Modpack Allows Flight

Zombe's Modpack is a great mod pack that contains many mods that allow you to do things like fly, control minecarts, teleport, change the time, control the cloud height and much, much more.

This is a very recommended mod and it's available for download here:
Zombe's Modpack