Toggler Mod 1.8, 1.7.10, 1.7.2 saves you from having to hold down buttons on your keyboard. For example, instead of holding down the spacebar to stay afloat while swimming you could simply press the key that you have set for ToggleJump. Now Minecraft will act exactly like you're holding down spacebar until you either press the toggle key again or until you press spacebar yourself.