First thought would be a 595 shift register, you get a heck of a lot more than 10 outputs with just 3 inputs. 8 outputs per chip, daisychain the chips without using any more pins from the arduino. Very versatile.
But if you're really looking for just one pin maybe you need to find something that works with serial communication... I wouldn't know much about that.
If I understand your question correctly you want to send PWM to one of 10 wires using as few Arduino outputs as possible.
Using 3 pins you can use the ShiftPWM library (I think that's what it is called) that simulates PWM using 595 shift registers. I have had up to 32 PWM outputs driving leds simultaneously using an Uno.
Using 2 pins you could clocking a CD4017 IC with one pin (each clock pulse turns on the next output from the chip), feeding that into a transistor to switch the PWM line to one of 10 outputs. Look for the datasheet to see how it works.
I have some indicators that display a number from 0 to 9, depending on which one of 10 wires is powered.
I want to stack 6 of these together to create a 6-digit display.
With 10 inputs per digit, 6 digits would need 60 wires. If I use a BCD-to-decimal decoder, I can get away with 4 wires per digit, but that still takes up 24 digital outputs on the Arduino.
If I buy a Mega, I can make it work, but I was hoping to do it with my Uno somehow.
I'll do some reading on the 595 Shift registers, and the LED bar graph chips to see if they can do what I need... Thanks again!
Whoops... here's the electrical info from the datasheet:
Input Voltage:
4 ±0.25 D.C.
Input Current:
105mA Nominal @ -20°C; 164mA Max. @ -54°C
D.C Terminal Resistance:
38? ±5% @ -20°C
Input Power:
0.42 Watts Nominal @20°C; 0.68 Watts Max. @ -54°C
They're from old aeroplane gauges. They look like odometers from a car (painted numbers on little wheels), except each digit is individually controllable.