user2838: I would like to manage many LEDs from my Arduino - 12 or so - but I do not have the available digital pins to do this. Only one LED needs to be on at one time. Instead, I was hoping to control these with an analog pin. I was wondering if there is some sort of switch out there which can take an analog signal and, based on the value, direct a 5V current to a certain LED.
I realize that I could use a second Arduino for this, but I am trying to avoid that.
Thanks in advance for any help!

user2839: You can accomplish this digitally with a device called a decoder. For example, the 74154 takes 4 inputs and maps those to one of 16 outputs (depending on the binary coding of the inputs). From the data sheet:

The 74HC154; 74HCT154 decoders accept four active HIGH binary address inputs and
  provide 16 mutually-exclusive active LOW outputs.


user2881: If you have 4 pins available, you could use charlieplexing to selectively light up 12 led.

Alternatively you could use some IC. You could use the one Greg suggested. 
Or you could use a shift-register. This requires only 2 or 3 pins, an will enable you to light up any one or more leds at the same time. Most have 8 outputs, but you can connect one to the other (daisychain), so with 2 shift-registers you can individually turn on/off 16 leds. You can easily control these using arduino's shiftOut command.
You could also use a port-expander using I2C to talk to it. More complicated, and a bit more expansive. But also more powerful. It will require only 2 pins (A4, and A5).

2838: <p>I would like to manage many LEDs from my Arduino - 12 or so - but I do not have the available digital pins to do this. Only one LED needs to be on at one time. Instead, I was hoping to control these with an analog pin. I was wondering if there is some sort of switch out there which can take an analog signal and, based on the value, direct a 5V current to a certain LED.</p>

<p>I realize that I could use a second Arduino for this, but I am trying to avoid that.</p>

<p>Thanks in advance for any help!</p>
 2839: <p>You can accomplish this digitally with a device called a <em>decoder</em>. For example, the <a href="http://www.nxp.com/documents/data_sheet/74HC_HCT154.pdf" rel="nofollow">74154</a> takes 4 inputs and maps those to one of 16 outputs (depending on the binary coding of the inputs). From the data sheet:</p>

<blockquote>
  <p>The 74HC154; 74HCT154 decoders accept four active HIGH binary address inputs and
  provide 16 mutually-exclusive active LOW outputs.</p>
</blockquote>
 2881: <p>If you have 4 pins available, you could use <a href="http://en.wikipedia.org/wiki/Charlieplexing#Charlieplexing" rel="nofollow noreferrer">charlieplexing</a> to selectively light up 12 led.
<img src="https://i.stack.imgur.com/bedxM.png" alt="charlieplexing"></p>

<p>Alternatively you could use some IC. You could use the one Greg suggested. </p>

<p>Or you could use a shift-register. This requires only 2 or 3 pins, an will enable you to light up any one or more leds at the same time. Most have 8 outputs, but you can connect one to the other (daisychain), so with 2 shift-registers you can individually turn on/off 16 leds. You can easily control these using arduino's <code>shiftOut</code> command.</p>

<p>You could also use a port-expander using I2C to talk to it. More complicated, and a bit more expansive. But also more powerful. It will require only 2 pins (A4, and A5).</p>
