Another thorough Arduino article up over @ uCHobby – this time covering the details of interfacing and modifying analog gauges.

In this article I describe the simple setup and explain the code to drive analog meters using PWM outputs from an Arduino and the LCD Smartie program. I also replace the meter face to show the proper scale. Replacing the meter scale is very easy to do with most meters and can really ad some style to your project.

Aah the comforting motion of a bouncing meter needle –Link

USB Meters
DIY – USB analog gauges –Link

From the pages of MAKE:
USB Meters
The Net Data Meter from MAKE:11 p.133 –Link