I just noticed this, and hopefully someone in the know or maybe with an engineering background could explain it to me.

So I'm practicing plugged in, and I remember that my iPod's out of charge. I grab the end of my charger, and notice a strange buzz coming from my amp. If I let go of the charger, the buzz stops. I've noticed that the closer I get to my pickups, the louder the buzz gets. I plug in my iPod, and just touching it while it's plugged in generates the sound.

Any explanations?
Many guitars are very badly shielded. And all things that use electricity give off a 60Hz AC signal. When this gets into a guitar, it goes to your amp and is then amplified, and you get buzz. I have had the same thing where on a cold day, to warm up my fingers, I've held my hands near a lightbulb.

Using the grounded bridge and strings, which you touch, they use you as an antenna to pick up some stray electrical signals and keep them out of your guitar signal. Yet when you have an unshielded guitar cavity, this sometimes is not enough to keep out all the electrical signals so close contact with electrical things increases the hum.

If you want a very good example, just unplug your cord from your guitar and hear the hum, as the tip of the jack will pick up those signals.

The best ways to fix this are to shield your guitar cavities, make sure your bridge and strings are grounded, and to use star grounding.