GasCraft by Emasher
GasCraft is an official addon for Engineer's Toolbox. GasCraft adds several gases to the game which while all functioning like normal Forge fluids, behave like gases when in block form. Different gases have different uses.
Gases Framework is a lightweight API that makes it possible to create gases in minecraft. Originally created for Glenn's Gases, other mods can expand upon the framework.
GateCopy by denoflions
This mod adds a clipboard item that can copy the settings from a Buildcraft Gate and paste those settings onto another similar gate.