I'm going to take two ideas I've posted on Reddit and combine them here, as they're related, along with some updates to the original concepts.
The Charge Dimension
Accessing the Charge dimension requires a powered redstone line surrounding an altar. All pieces of redstone in the line must be powered. The altar consists of a 3x3 horizontal box outline of iron blocks, filled in the middle with a piece of endstone, atop which sits a redstone block. (The endstone is to make sure this is an endgame feature.) As soon as such an altar is powered, the redstone block turns into a red, 3D portal block which, when stood in, transports you to The Charge. An altar is generated on the other side wherever you spawn, though the coordinates in the Charge are 1:1 with the Overworld (unlike the 8:1 ratio of Nether coordinates.) Note that if either altar is loaded and the power to the outer dust line is cut off, the portal on that side closes and turns back into a redstone block until power is restored.
The Charge is a dimension focused on redstone. The sky is a red version of the End's starfield. Redstone ore would be abundant there, with a little bit of iron ore as well, but no other ores. Redstone-block structures would also be generated. The Charge equivalent of stone/endstone/netherrack is Charged Stone, which drops itself when mined (see the items section for more information). Just as the Nether changes physics for lava, the Charge changes physics for redstone. Specifically, touching a powered redstone dust while in the Charge will inflict 0.5 heart of damage per second you touch it (same is true while mining charged redstone dust). Charge mobs are immune to this type of damage as well as lightning damage. Redstone-block buildings (Charged Fortresses?) would generate with predefined redstone contraptions and traps inside, often with exposed redstone dust being a trap itself. Of course, the reward for braving these trapped buildings would be loot chests with redstone-based loot. In addition, though it never rains in the Charge, lightning is common. Occasional rivers flow through areas of the Charge as well (you'll see why in the mobs section!).
There is an obvious analog here to the Nether's glowstone: redstone lamps. These generate in singlets randomly, and always generate with a redstone block powering them on one of their sides.
Charge mineshafts will also generate, which have redstone torches as their only light (which, of course, hurt when you touch them, as they're powered). All rails in the mineshaft are powered, and some which happen to have torches next to them or redstone blocks spawned under them will of course be powered and painful. However, you may find a Zaptoad spawner here (see mobs section), which could be useful for farming.
The Charge would contain only custom mobs. Specifically, it would have the following:
Shocks: These mobs, which float like blazes, look like anthropomorphized electrical elementals. So like sparks with a mildly organic form and a face. Whenever they touch redstone dust, it becomes powered to level 15 (which remember, is harmful in the Charge!). In addition, they have a short range zapping attack that can deal 1 to 2 hearts of damage, depending on distance, from up to 2 blocks away. If they touch water, all adjacent water within 5 blocks becomes electrified--meaning if you're in water around them, you'll likely get electrocuted, taking a heart or more each second you're in electrified water. (Note: lightning striking water will electrify the surrounding 10 adjacent water blocks for 1 tick.) Killing a Shock will drop 0-3 redstone dust and 0-1 lightning rods (see the items section for more info). They will spawn on any non-water block, basically, but spawn more often inside Charge Fortresses.
Electric Eels: They swim in the rivers and electrify water in a 1-block radius from them. That's all. They drop 0-1 redstone dust on death.
Zaptoads: Only spawn in Charge mineshafts, generally from spawners, though they may hop out of a mineshaft and into the open. They're redstone-infused frogs. They can hop up to 3 blocks high and 2 blocks in distance. They hurt you if they touch you; they do NOT power redstone lines the way Shocks do. They also have a 10% chance of inflicting a few seconds of poison on you when they touch you. Killing them drops 0-2 redstone dust (see the pattern with these mob drops yet?) and 0-1 red slime.
Charged Stone: The most common item in the Charge. Emits a redstone signal of strength 1 from all sides, but otherwise acts like normal stone (and looks like a stone block but with a slight red tint).
Lightning rod: Dropped from Sparks, you can place a lightning rod in the Overworld, where they appear like torches, only with no tip and made of metal. Whenever it rains, the chances of a lightning strike are increased at the position of any lightning rods. When struck by lightning, the rod gives off a redstone signal of strength 15 for two ticks. Can be used to make charged creepers or zombie pigmen, or simply as an inclement weather detector. Can also be used in the recipes for the redstone transceiver.
Redstone transceiver: Finally, a vanilla wireless redstone solution that doesn't require exploits. They're crafted with a repeater in the middle and two lightning rods, one on either side. These components are directional like repeaters, with an input side and an output side. When a signal comes in their input side, they transmit this signal wirelessly to all transceivers within 15 blocks horizontally and 2 blocks vertically (i.e. 2 above and 2 below). The signal DOES degrade at the same rate as redstone dust (1 power lost per block traveled), but is omnidirectional and passes through all types of blocks. A transceiver will output the maximum power among both wireless signals and its own input. Note that this means all transceivers in an area will equalize rather than ever bouncing back and forth, as the maximum will be the same for all of them since they transmit their own inputs.
Red slime: Dropped from Zaptoads, red slime can be placed on the ground. They have the size and hitbox of a carpet, but they slow down anything that walks on them, including players and mobs. They do NOT reduce fall damage like green slime, as they're too thin. They can also be used in the recipe for insulated redstone.
Insulated redstone: Crafted with eight redstone dust surrounding one red slime, producing 8 insulated redstone, an insulated redstone is basically directional redstone. It will carry a signal with zero delay, like redstone dust, but it will do so only along one axis (so in two opposing directions). This allows you to place insulated redstone lines adjacent to each other with no interference (or an insulated line next to a regular dust line with no interference, either). I'd also say you could place the lines on walls, but that might be pushing it programming-wise, considering that would usually entail two redstones in the same block at corners >_<
Redstone crossbridge: Crafted with 5 insulated redstone in a cross shape and (maybe) 4 stone in the corners, this is simply a crossing component. Redstone signals in the east side are copied to the west side and vice-versa; redstone signals in the north side are copied to the south side and vice-versa. This way we can much more cleanly cross our wires (insulated or normal dust) without interference.
Comments? Criticisms? Suggestions? Support? Let me know!