Utility Worlds Mod 1.8, 1.7.10, 1.7.2 adds two portals (blocks) that can be crafted, the Mining Portal and the Void Portal.

• To use a portal, simply craft it and place it in the world, then right-click it. This will teleport the player to a new dimension, one separate for each crafted portal.
• At the location where the player arrives in the new dimension, a return portal is placed which can be used immediately.
• Portal blocks can be picked up and moved. Return portals can only be moved within their original dimensions.
• Currently not well suited for creative mode. Portal blocks are easily destroyed in creative and cannot be recreated yet.