Some more ideas

I tried changing my blinking LED code to select an LED in my array of LEDs based of the reading of the potentiometer. I hope to be able to add some LEDs to my board to be able to create 2 axis and read the values off of my old Joystick. The game port is throwing me off because of the timer capacitor thing. I'll figure it out. In the meantime I need to buy myself a multimeter so I can figure out a lot of stuff.

In the mean time, I think I'll try a vumeter. I don't see why I couldn't just plug an audio signal into a rectifier and then into an analog pin on the arduino. Of course, a line out will only put out about + or - 1V. I have some LF347 op-amps that would be easy enough to get the signal up to 5 vols.

Another thing that I want to try in the mean time is to use the op-amps to build a summer for an interrupt that triggers on 4 inputs. The arduino, it seems is limited to set interrupts on 2 pins. The real way to do this would be with another chip and have that tied to the pin that triggers an interrupt. The op-amp way would be pretty easy for as many triggers as I'd please.

And yet another thing I want to play with, is an old 4 digit switch that I pulled out of some spectrometer or something. The problem is that each digit has 4 wires making a total of 16 wires plus a rail, making a total of 17 wires. I guess the way to read all 4 digits would be to split the rail in 4, and connect the 4 rails to there own pins, then connect the 4 wires for each digit to all the other corresponding wires on the other digits. This would use in total 8 pins. I have 2 of these 4 digit switches, so 2 of these switches would only use 12 pins on the arduino. If you've seen the multiple joystick tutorial, this uses the same concept.