Ley Lines in Gamma World and Mutant Future

What people think as ley lines are actually power conduits that were used to send exotic forms of radiation across the globe. With time and erosion, many now leak or have broken. In either case, the energy usually impacts something in the vicinity. An easy way to use this is mutation modifiers (Wisdom from the Wastelands: #20), having all mutants gain the same modifier to one of their mutations selected randomly. If you don't want to fiddle with powers, there is always the landscape itself:  http://d-infinity.net/blog/derek-holland/mutant-minerals-and-plants  or http://d-infinity.net/blog/derek-holland/goo-pools-mutant-future  or  http://d-infinity.net/blog/derek-holland/ordered-matter-mutant-future  plus modified technology (Wisdom from the Wastelands issues with Superscience artifacts and 50: Artifact Quality).

In any case, these are meant to be tools to allow the GM to bring out the weird in the setting. They also make good locations as treasure- those who control them, make the loot.