While most USB-charged Apple products like the iPhone and iPad come with a USB charging cable in the box, there is a thriving third-party market for these easily lost accessories. Dexim's $20 Visible Green USB-Dock Connector cables have a distinctive twist: they use electroluminescence to "visibly show the electrical current flowing through the cable". Completing the illusion is the fact that there are multiple speeds that the current can "flow", adjusting with the battery life of the device it's charging.
While perhaps not the most practical iPhone charger, particularly for bedside nighttime charging, the Visible Green cable is certainly the coolest.
Dexim's Visible Green cables are available via a number of retailers, including Amazon and others.