using the touchscreen from a distance Is there anything that might be able to mimic a finger (by changing the capacitance of the touchscreen) without having to make much physical contact? For example, an electric field that changes the capacitance? Or something similar? (presumably it would require a power source)

I realize similar questions have been asked, such as this one: What is the iPod touch&#39;s screen sensitive to?

What I'm wondering is if you could mimic a finger with a electrically charged or powered device...?
There many styluses in the market now a days with some good and innovative ideas.

There are even ways to create a home made stylus. Which usually uses you hands static energy. There are some good How To Guides on internet which can help you.

Some marketed styluses use some kind of rubber. To get phone recognize the touch like Ten One Design Pogo Stylus.

One most advanced stylus would be Studio Pen from by-zero. According to there website they use patented technology combining ultrasound and infrared technologies with sophisticated algorithms. In short (according to them) they type of ditch this touch sensitivity all together and use some "ultrasound and infrared technologies" to get the position of the pen tip and that is then feed to the iDevice using Receiver which is connected to the charging Port.

Hope that helps:).