AddedCompat: Alchemy by SkylordJoel
AddedCompat revolves mostly around alchemy, a spiritual successor to Equivalent Exchange 3 for 1.6.2. Currently, IC2 is supported but plans to support more mods exist.
Advanced Fluxian Tools by tgame14
A mod that adds broad range tools into minecraft that are powered by redstone flux
Applied Energistics by AlgorithmX2
A Mod About energy, and matter. Oh wait thats everything...
BuildCraft by SpaceToad, BuildCraft Team
Extending Minecraft with pipes, auto-crafting, quarries, engines and much more!
ChemLab by Itaros
This mod adds the ability to play with items at molecular level. Hardcore automation experience awaits you!
tech addon worldgen survival
Compact Solar Arrays by cpw
Compact Solar Arrays, an Industrial Craft 2 mod that adds in three new Solar Panel type blocks: Solar Arrays. Solar Arrays condense 8 (Low Voltage), 64 (Medium Voltage) or 512 (High Voltage) Industrial Craft 2 solar panels into a single block. This significantly reduces the CPU impact of large amounts of Solar Energy gathering so is a common server enhancement.
CompactWindmills by Aroma1997, Schillaa
This mod/addon for IndustrialCraft2 adds CompactWindmills to the game. They are basically More Windmills within one Block: Availible in ELV(8EU/t), LV(32EU/t), MV(128EU/t), HV(512EU/t) and EV(2048EU/t). They save CPU if used in big power plants.
DenPipes by denoflionsx
DenPipes is a small addon for Buildcraft that implements various pipes that aid in making builds smarter and more compact
addon opensource tech
Dynamic Liquid Tanks 2 by DocRedstone,
Dynamic Liquid Tanks is a mod that is based upon storing liquids in Minecraft in a limitless combination using multi-block structures, so that they look just the way that you want them to!!
ElectriCraft adds a new way to transport and store RotaryCraft power. Like ReactorCraft, this mod is dependent on RotaryCraft.
Ender IO by crazypants
Compact conduits, painted things and access to your stuff through an eye of ender.