Modloader by Risugamihttp://www.minecraftforum.net/topic/75440-v181-risugamis-mods-everything-updated/
API
Modloader MP Unofficial by jamioflan
http://www.minecraftforum.net/topic/182918-181smp-flans-mods-planes-ww2-guns-vehicles-playerapi-moods-mputils-teamsAPI
Minecraft Forge 1.1.1 by SpaceToad and Eloraam
http://www.minecraftforum.net/topic/514000-api-minecraft-forge/API (the glue of Technic)
Industrial Craft 2 1.15 by Alblaka and the IC2 Team
http://forum.industrial-craft.net/index.php?page=Thread&threadID=767CORE MOD
Adds electricity, advanced machines and nuclear engineering along with two new ores.
Buildcraft 2.2.1 Complete Package by SpaceToad
http://www.mod-buildcraft.com/http://www.minecraftforum.net/topic/682920-181-buildcraft-221-pipes-quarry-auto-crafting-building-engines/CORE MOD
Adds pipes, engines, quarries and oil, among other infrastructure machines.
RedPower Pre2 (RP2pr2)* by Eloraam
http://www.eloraam.com/http://www.minecraftforum.net/topic/365357-181-173-eloraams-mods-rp2pr2-redpower-v171-integrated-redstone-now-redpower-logic-redstone-pipe/CORE MOD
Adds advanced redstone wires, lamps, switches, gates and arrays.
* This is an incomplete and work-in-progress mod. Keep this in mind when you are playing with panels and redstone wire
Equivalent Exchange V4.16 by x3n0ph0b3
http://www.minecraftforum.net/topic/364525-181-equivalent-exchange-v406/CORE MOD
Adds alchemical recipes, items of extreme cost and power
Minefactory Reloaded 1.2.2 by power crystals
http://www.minecraftforum.net/topic/554413-173minefactory-reloaded-112-smp/CORE MOD
Adds conveyor belts and automatic harvesting options
Mo' Creatures V2.13.2 by DrZhark
http://www.minecraftforum.net/topic/81771-v181-mo-creatures-v213-with-smp/Adds a ton of new mobs, both passive and hostile
Millenaire 1.6.9 by Kinniken
http://www.minecraftforum.net/topic/227822-181-millenaire-npc-village-161-new...
Breathes a giant wave of life into the world. Villagers, NPCs and an economy system for it
Somnia v15 by MALfunction84
http://www.minecraftforum.net/topic/162771-181-somnia-v14-sspml/Sleeping now allows the world to continue on instead of skipping ahead like in vanilla.
Optifine 1.8.1 by sp614x
http://optifog.blogspot.com/http://www.minecraftforum.net/topic/249637-181-optifine-hd-b-fps-boost-hd-textures/Performance mod. Some people absolutely need this mod to even play Minecraft.
Treecapitator by DaftPVF
http://www.minecraftforum.net/topic/124117-18-daftpvfs-mods/#treecapitatorRealistic tree chop-down action. Take out the bottom of a tree out with an axe the whole thing falls
MAtmos 1.8.1 r6
http://www.minecraftforum.net/topic/379925-181-matmos-r6-environmental-sound-atmosphere-simulator/Adds ambient noises and sounds to the game
Rei's Minimap 2.4 by ReiFNSK
http://www.minecraftforum.net/topic/482147-19presep25-reis-minimap-v21-guinea-pig-version/Adds a small minimap to the game and allows you to set waypoints so you don’t get lost
Risugami's Recipe Book 1.7.3 by Risugami
http://www.minecraftforum.net/topic/75440-v181-risugamis-mods-everything-updated/Gives you a portable guide that lists every possible recipe via a crafting table in the game. There is a lot.
Convenient Inventory
http://www.minecraftforum.net/topic/504091-v173-convenient-inventory-19/Click stacks and single items all over the place, tweaks inventory movement
The Allocator and The Fan by Pfaeff
http://www.minecraftforum.net/topic/200272-v181-pfaeffs-mod-ssp-v085-allocator-jump-pad-and-more/Adds the Allocator to shift items to and from chest, and The Fan to blow it all around
Buildcraft Teleport Pipes by Zeldo
http://www.minecraftforum.net/topic/653775-173-buildcraft-teleport-pipes-06-chunkloader-added/Allows you to teleport items without having a large pipeline
Zeppelin v16 by blakmajik
http://www.minecraftforum.net/topic/488434-181-zeppelin-015-wip/Build an airship and fly in your Minecraft world
Nature Overhaul v1.3 by Clintonxa
http://www.minecraftforum.net/topic/191599-v181-nature-overhaul-v13/Trees
Trees now live, die and spread around your Minecraft world spreading new plant growth far and wide.
Xie’s Farming v1.7b by deathrat converted to Forge then to 1.8